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Library of Congress Subject Headings (LCSH)

Library of Congress Subject Headings (LCSH) is the list of headings produced from the subject authority file maintained by the United States Library of Congress for use in bibliographic records. It is popularly known by its abbreviation as LCSH and is sometimes used interchangeably with the phrase subject authority file. LCSH is a controlled vocabulary. A single word or phrase is chosen to represent each concept that is included, and synonyms are provided as see-references to that heading. It also indicates relationships between and among headings. It is not a true thesaurus, though, because for historical reasons it does not completely conform to the international standard on thesaurus construction. LCSH comprises the complete alphabetic list of terms to be used as controlled vocabulary for subject concepts by the catalogers of the Library of Congress and other libraries to provide such controlled subject access to surrogate records. LCSH has been used in cataloging since 1898 at the Library of Congress in assigning subject headings to facilitate subject access to the resources in its library catalog.

LCSH is a multidisciplinary vocabulary that includes headings in all subjects, from science to religion, to history, social science, education, literature, and philosophy. It also includes headings for geographic features, ethnic groups, historical events, building names, etc. Library of Congress Subject Headings (LCSH) is the most widely used subject vocabulary in the world. It is the model for many other vocabularies in English and other languages and has been translated into numerous languages. The strongest aspect of LCSH is that it represents subject headings of the Library of Congress, the national library of the United States, one of the richest of national libraries of the world. The administrative and managerial machinery of LC has made it possible for LCSH to stand out as an undisputed leader. LCSH is also used as indexing vocabulary in a number of published bibliographies.

Library of Congress Subject Headings LCSH

LCSH comprises a thesaurus or a controlled vocabulary of subject headings which is used by a cataloger or an indexer to assign subject headings to a bibliographic record to represent the subject of a work he/she is cataloging. LCSH contains the preferred subject access terms (controlled vocabulary) that are assigned as an added entry in the bibliographic record which works as an access point and enables the work to be searched and retrieved by subject from the library catalog database. The controlled vocabulary identifies synonym terms and selects one preferred term among them to be used as the subject heading. For homonyms, it explicitly identifies the multiple concepts expressed by that word or phrase. Cross-references are used with headings to direct the user from terms not used as headings to the term that is used, and from broader and related topics to the one chosen to represent a given subject.

The fortieth edition of Library of Congress Subject Headings (LCSH 40) contains headings established by the Library through January 2018. The headings included in this list were obtained by creating a file consisting of all subject heading and subdivision records in verified status in the subject authority file at the Library of Congress. There were 342,947 authority records in the file then.

The subject authority database from which the headings in this edition were drawn indicates that the file contains approximately 24,390 personal name headings of which 23,272 represent family names, 10,034 corporate headings, 6 meeting or conference headings, 481 uniform titles, 242,511 topical subject headings, and 61,885 geographic subject headings. There are 764 general USE references, 4,351 general see also references, 299,751 references from one usable heading to another, and 362,646 references from unused terms to used headings.

The creation and revision of subject headings is a continuous process. Approximately 5,000 new headings, including headings with subdivisions, are added to LCSH each year. Proposals for new headings and revisions to existing ones are submitted by catalogers at the Library of Congress and by participants in the Subject Authority Cooperative Program (SACO). More information on SACO may be found at <URL>. Approved proposals become part of the online authority file of subject headings at the Library of Congress, from which various publications are created.

Five services provide information about new and revised headings. First, a distribution service supplies the subject headings in the MARC 21 authorities format via Internet FTP on a weekly basis to supplement the master database file of subject authority records. Second, L.C. Subject Headings Monthly Lists are a timely source of information about new and changed subject headings, class numbers, references and scope notes. The lists are posted monthly to the World Wide Web at Third, Classification Web provides World Wide Web access to Library of Congress Subject Headings and Library of Congress Classification to subscribers. Fourth, subject authority records are included in the Library’s Web authorities service and may be searched and viewed at Fifth, subject authorities are freely available for searching and download through the Library’s Linked Data Service at 


  • LCSH Use With Auxiliary Aids
  • LCSH History
  • Component of Entries in LCSH
    • Headings
    • Class Numbers
    • Scope Notes
  • References: The Relationship Between Headings
    • The Equivalence Relationship: USE References
    • The Hierarchical Relationship: Broader Terms and Narrower Terms
    • The Associative Relationship: Related Terms
    • General References
  • Subdivisions
    • Categories of Subdivisions
    • Topical Subdivisions
    • Form Subdivisions
    • Chronological Subdivisions
    • Geographic Subdivisions
    • Geographic Subdivision and Place Names Divided by Topic
    • Free-floating Subdivisions
  • Pattern Headings
  • Categories of Headings Included in the List
  • Categories of Headings Omitted from the List
  • Filing Arrangement
  • LCSH Examples
  • LCSH Assigning and Constructing
  • LCSH Twenty-Percent Rule
  • LCSH Articles and News
  • LCSH Authority Control
  • LCSH Quiz
  • LCSH Tools and Resources
  • LCSH Videos
  • Examples of Some Controversial LCSH Headings
  • Examples of Some LCSH Headings You Never Know it Existed
  • Conclusion


LCSH 40 should be used with several auxiliary aids. Most important of these is the Subject Headings Manual (2008 edition), which is available through Cataloger’s Desktop, a subscription-based online documentation service. The instruction sheets comprising the Manual may also be freely downloaded from LC’s web site at

The Manual contains the same instructions used by subject catalogers at the Library of Congress in their daily work. Although some of the instructions describe internal Library of Congress procedures, most of them are essential for those who wish to understand and to apply Library of Congress subject headings correctly. Reference will be made to the Manual when additional information on a topic is described there.

Headings for names of persons, corporate bodies, jurisdictions, uniform titles, and other headings traditionally thought to be capable of authorship may be assigned as subject headings. Authority records for these headings reside in an online file of name headings at the Library of Congress. These records may be searched and viewed through the Library’s Web authorities service at and in Classification Web. These records are also distributed via FTP, and they must be consulted for the authorized form of name headings. When name headings have been printed in LCSH, they have usually been borrowed from the name authority file. The full reference structure and additional authority information will appear only in the name authority file.

Questions on the publications or their content should be referred to:
Policy and Standards Division Library of Congress 101 Independence Avenue, S.E. Washington, D.C. 20540–4260 Email:


Like its predecessors, this edition of LCSH continues to be an accumulation of the subject headings established at the Library of Congress since 1898. In 1897 after the Library had been moved from the U.S. Capitol into its resplendent new building, it became apparent that a new subject catalog was necessary to reflect more specifically the vast array of subjects of the books contained in the Library’s rapidly growing collections. The Library decided that a dictionary catalog instead of an alphabetic-classed or a classed catalog should be adopted to complement the new classification system that would replace Thomas Jefferson’s system. Using the List of Subject Headings for Use in Dictionary Catalogs (A.L.A. list), prepared by a committee of the American Library Association and published in 1895, as a base text, blank leaves that trebled the size of the original volume were added and the copies were bound in flexible leather. The A.L.A. list, several other lists of subject headings, and many reference books were consulted as sources for new subject headings. New subjects also arose in the daily cataloging done at the Library. By the spring of 1898 decisions were made and preliminary arrangements were in place. Actual work on the new subject catalog began simultaneously with the printing of the first author cards in July 1898.

The first edition of the Library of Congress list, called Subject Headings Used in the Dictionary Catalogues of the Library of Congress, was printed in parts between 1909 and 1914. Supplementary lists were issued as required, followed by a second edition in 1919. Later editions were published at irregular intervals. The title was changed to Library of Congress Subject Headings when the eighth edition was published in 1975.

Since the inception of the list, headings have been created as needed when works were cataloged for the collections of the Library of Congress. Because the list has expanded over time, it reflects the varied philosophies of the hundreds of catalogers who have contributed headings. Inconsistencies in formulation of headings can usually be explained by the policies in force at the varying dates of their creation.


Headings are listed in boldface type, e.g., Alphabet, Life on other planets, Nuclear physics. A heading may be followed by the legend (May Subd Geog), which shows that the heading may be subdivided by places according to the rules in the Manual, and by class numbers. Scope notes giving guidance in the meaning or application of a heading may follow in separate paragraphs. References associated with the headings are then listed in groups, followed by subdivisions of the subject headings, which may have any or all of the above-named elements. Each of these components is described below.


Subject headings may consist of one word or several. A one-word heading is usually a noun, Viscosity, Dogs, or Schools, for example. Concepts are normally named in the singular and objects in the plural, though exceptions may be found.

Two-word headings usually contain an adjective and a noun. These may appear in normal word order, as with Nuclear physics, Local taxation, and Pumping machinery, or in inverted form. Inversion is common with adjectives describing language or nationality, such as Lullabies, Urdu; Songs, French; Art, American; and Drawing, Australian. Other types of headings may also be inverted in order to bring the noun into the initial position, such as Love, Maternal and Injections, Intramuscular. The current policy is to use normal word order for topical headings except for headings with language, nationality, or ethnic adjectives, headings qualified by time period, such as Art, Medieval, headings qualified by artistic style, headings with the adjective Fossil, and certain music headings.

Although the original intent was that subject headings would follow a dictionary plan instead of an alphabetic-classed plan, the list reflects a reluctance to disperse related entries. Many headings were originally constructed in a manner that placed the name of a class first through the use of subdivisions, through inversion, or through parenthetical qualification. Examples of these are: Photography—Studios and dark rooms; Geology, Stratigraphic—Cenozoic; Railroads— Timetables; Vacation schools, Religious; Art, Byzantine; Cooking (Fish); and Trials (Forgery). These headings and many similar ones continue to exist in the list today.

Names of geographic features have traditionally been inverted in order to place a significant word in the initial position instead of the generic word. For example, Lake Erie is formulated as Erie, Lake so that the distinguishing part of the name, Erie, appears first.

When more than two words are used in a heading, the heading may include conjunctions and prepositional phrases. Headings with the word and may express a reciprocal relationship, as in Technology and civilization, or they may combine two headings so similar that they are often treated together in one work, as with Bolts and nuts. Headings with prepositional phrases may be inverted, as in Criminal justice, Administration of, or in normal word order, as in Photography of birds, Occupational therapy for children, and Prediction of scholastic success. The Library has changed some headings with inverted prepositional phrases into headings with subdivisions or phrase headings on a case-by-case basis.

Class Numbers 

Approximately 89,577 subject authority records contain Library of Congress class numbers, which generally represent the most common aspect of a subject. If several aspects of a subject are covered by different class numbers, an explanatory term is included to indicate the specific discipline. For example, 

Hydraulic presses 

Norwegian language

Gums and resins 
[QD419–QD419.7 (Chemistry)]
[SB289–SB291 (Culture)]
[TP977–TP979.5 (Chemical technology)

Class numbers are added only where there is a close correspondence between the subject heading and the provisions of the Library of Congress classification schedules. Because these, as well as the subject heading list, are subject to continuous revision, the class numbers in the LCSH should not be used without verification in the latest editions of the schedules. 

Scope Notes 

Scope notes are provided when needed to ensure consistency of subject usage by specifying the range of subject matter to which a heading is applied in the Library’s catalogs, by drawing necessary distinctions between related headings, or by stating which of several meanings of a heading is the one to which its use in the Library’s catalogs is limited. These notes appear in the list immediately following the headings with which they are used. A typical example may be found under the heading Home-based businesses. The Manual contains a full description of the types of scope notes and their use. Over 11,944 headings have scope notes in LCSH


LCSH contains cross-references constructed at different times according to different philosophies. Some references from specific to general topics remain as a legacy past practices. For many years cross-references were made to subjects “likely to be of interest to the user” who consulted a subject heading. In 1985 new rules for making references were put in place. As a result more attention is being paid to hierarchical relationships, and superfluous or inaccurate references are deleted from the list when found. These rules are described fully in the Manual.

The Equivalence Relationship: USE References 

USE references are made from an unauthorized or non- preferred term to an authorized or preferred heading. Under the heading referred to, the code UF (Used For) precedes the term not used. The codes USE and UF function as reciprocals.

Cars (Automobiles)
   USE Automobiles

   UF Cars (Automobiles)

The word USE and the code UF appear only in front of the first reference if several references are present.

Raw foods 
    UF Food, Raw [Former heading]
          Uncooked food
          Unfired food

A reference that is an earlier form of a heading is followed by the legend [Former heading].

    UF Data bases [Former heading]

USE references are made from synonyms, variant spellings, variant forms of expression, alternate constructions of headings, and earlier forms of headings. USE references are also made when it has been decided that words should not be used as a heading even if the heading and the unused words are not truly synonymous. Headings having more than one word frequently have USE references from the words not chosen as the entry element. USE references are not normally made in this list from abbreviations, unless they are in widespread use, nor are they generally made from foreign language equivalents of topics.

USE references are often omitted if they would begin with the same word as a broader term needed for hierarchy. That is,

Exterior lighting
    BT Lighting

is made instead of

Exterior lighting
    UF Lighting, Exterior

The Hierarchical Relationship: Broader Terms and Narrower Terms

Subject headings are linked to other subject headings through cross-references now expressed as Broader Terms (BT) and Narrower Terms (NT). The code BT precedes a subject heading representing, according to current policy, the class of which the heading is a member. The code NT precedes a subject heading representing, in most cases, a member of the class represented by the heading under which the NT appears. The codes BT and NT function as reciprocals. A heading appearing as a BT must be matched by the reversed relationship as an NT, as demonstrated by the following example:

Exterior lighting 
    BT Lighting

    NT Exterior lighting

A heading is normally linked to the one immediately next to it in the subject heading hierarchy. Since the referenced headings are linked in turn to other headings, references for distant relationships are no longer made. References leading to two or more levels in a hierarchy reflect an obsolete practice.

Making hierarchical relationships explicit creates a system in which superordination and subordination are clearly stated. Headings created after 1984 should follow these principles. Headings established before 1985 are reviewed on a gradual basis. Their references are being changed to conform to current rules. Until this review is completed, the list will contain references that do not reflect hierarchy.

The making of hierarchical references creates the ability to systematically find headings that are more general or more specific than the heading being consulted. No matter the level at which one enters the hierarchy, one can follow either BTs or NTs to find the broadest or most specific heading available. The following headings illustrate this:

    BT Transportation
    NT Motor vehicles

Motor vehicles
    BT Vehicles
    NT Trucks

    BT Motor vehicles
    NT Dump trucks

Dump trucks 
    BT Trucks

By following the NTs it is apparent that the most specific heading is Dump trucks. By following the BTs it is apparent that the broadest heading is Transportation.

In the past, many hierarchical references were omitted when the narrower heading began with the same word as the broader heading. For example, the heading Schools of architecture does not contain the BT Schools. It was believed that alphabetic proximity eliminated the need for a hierarchical cross reference to a heading filing immediately adjacent. Broader headings are gradually being added if required by hierarchical principles regardless of alphabetic proximity.

The Associative Relationship: Related Terms 

The associative relationship, expressed by the code RT meaning Related Term, links two headings that are associated in some manner other than by hierarchy. For example,

    RT Ornithology

    RT Birds

According to current policy few headings will be linked by associative references until the hierarchy in the list has been thoroughly reviewed.

General References 

A general reference is a reference made not to specific individual headings but to an entire group of headings, frequently listing one or more headings by way of example. It was formerly considered impractical to list as specific references all of the individual headings encompassed by a broader heading, even though such specific references would have been theoretically logical and proper and even though the individual headings were printed in LCSH. Instead, general see also references have been made, retaining the code SA, such as 

Woodworking industries 
    SA names of specific industries, e.g., Furniture industry and trade 

It is expected that each library will make specific references to each individual industry about which the library has works. Many general references will gradually be replaced by specific references to narrower headings. 

General references have also been made from a generic heading to a group of headings all beginning with the same word: 

SA headings beginning with the word Chemical 

Other general references may lead to subdivisions: 

Economic history 
    SA subdivision Economic conditions under names of countries, cities, etc., and under classes of persons and ethnic groups 

General USE references also are made: 

Access control 
    USE subdivision Access control under types of archives, records, computers, computer networks, and statistical and data-gathering services, e.g., Computers—Access control; Psychiatric records— Access control 

Such general references to subdivisions do not necessarily indicate that the subdivisions are free-floating.


The application of Library of Congress subject headings requires extensive use of subject subdivisions as a means of combining a number of different concepts into a single subject heading. Complex topics may be represented by subject headings followed by subdivisions. Some subdivisions are printed in LCSH but a greater number of subdivisions may be assigned according to rules specified in the Manual. Only a fraction of all possible heading-and-subdivision combinations are listed in LCSH.

In order to facilitate reading the list, initial parts of a heading with subdivision are suppressed in printing. Instead, subdivisions appear in the list following a long dash, without repetition of the heading. For example,


was produced from a machine-readable record with the words Massachusetts—Antiquities. If two subdivisions are used, the main heading and the first subdivision are replaced by two long dashes:

    — —Colonial period, ca. 1600–1775
    — —New Plymouth, 1620–1691

These are carried in subject authority records as Massachusetts—History—Colonial period, ca. 1600–1775 and Massachusetts—History—New Plymouth, 1620–1691. When a heading has many subdivisions that are further subdivided, such as United States—History, the dashes help to align the subdivisions properly.

Categories of Subdivisions

Four categories of subdivisions are generally recognized: topical, form, chronological, and geographic. Each category is described separately below, and examples may be found in LCSH. Instructions for assigning them appear in various sections of the Manual.

Topical Subdivisions

Topical subdivisions are used under main headings or other subdivisions to limit the concept expressed by the heading to a special subtopic, e.g., Corn—Harvesting, Automobiles— Motors—Carburetors, and Women—Employment. Many topical subdivisions are omitted from the printed list. The rules for their application are found in the Manual and in general references printed under the generic headings in LCSH.

Form Subdivisions 

Form subdivisions are used to indicate the form in which the material on a subject is organized and presented (e.g., congresses, dictionaries, periodicals) and as such are added as the last element to any heading. Form subdivisions represent what a work is rather than what it is about. They can generally be used under any topic, and therefore are seldom printed in LCSH. Nevertheless, a few instances occur in the list, usually because they were established and printed before 1974 when they became free-floating, e.g.,

Massachusetts—History—Colonial period, ca. 1600– 1775—Juvenile literature 

United States—History—Periodicals

Most form subdivisions are indicated in the list by a general see also reference under the heading representing the form as a whole, e.g.,

    SA subdivision Periodicals under specific subjects, e.g., Engineering—Periodicals; United States— History—Periodicals

Guidance on the use of many specific form subdivisions, such as —Abstracts, —Catalogs, —Dictionaries, —Digests, — Handbooks, manuals, etc., —Pictorial works, —Tables, and others, is given in the Manual.

Chronological Subdivisions 

Chronological subdivisions are used to limit a heading or heading-and-subdivision to a particular time period. Under names of countries and other jurisdictions or regions are printed specific topical subdivisions and the chronological subdivisions that may be used with them. The date subdivisions given under United States—Economic conditions, United States—History, and United States—Politics and government are illustrative.

When topical headings contain chronological subdivisions not preceded by the subdivision —History, the subdivisions are usually established and printed in LCSH, e.g.,

Philosophy, French—18th century 

Art, Chinese—To 221 B.C.

Geographic Subdivisions

The designation (May Subd Geog) after a subject heading or subdivision indicates that a geographic location may follow the heading or subdivision. The designation (Not Subd Geog) after a subject heading or subdivision indicates that a decision has been made not to divide a particular heading by geographic location. Omission of either designation normally means that the heading has not yet been reviewed to determine whether geographic subdivision is possible or desirable; geographic location should not therefore be used.

Instructions for subdivision by place may occur under an individual heading in a scope note, but a full description of the rules is given in the Manual. Generally, if the geographic entity is the name of a country or is larger than a single country, the established name is placed immediately after the heading or subdivision that has the code (May Subd Geog). Labor supply (May Subd Geog) means that place follows the subject, as in Labor supply—France. If the geographic entity is the name of a region or geographic feature within a country, the name of a state or province, or the name of a city, then the name of the country it is in generally precedes the name of the smaller geographic locality. The result of this practice is to gather most of the localities as further subdivisions under the name of the country, as with Labor supply—France—Paris.

The major exception to interposing the name of the country is that three countries — the United States, Great Britain, and Canada — do not serve as gathering devices for smaller jurisdictions or geographic entities. The names of states, constituent countries, and provinces, respectively, instead of the country name, serve as gathering devices for the smaller jurisdictions or geographic areas. Additional exceptions to the general rule stated above are described in the Manual.

If a heading contains both a geographic subdivision and topical or form subdivisions, the location of the geographic subdivision depends on which elements can be subdivided by place. As a general rule, place follows the last element that can be divided by place. Following this rule for the heading from LCSH with subdivisions below

Construction industry (May Subd Geog)
— —Law and legislation (May Subd Geog)
—Government policy (May Subd Geog)
—Mathematical models

will result in these combinations:

Construction industry—Italy 

Construction industry—Italy—Finance 

Construction industry—Finance—Law and legislation— Italy 

Construction industry—Government policy—Italy 

Construction industry—Italy—Mathematical models

Few geographic subdivisions are printed in LCSH. For example, the heading Petroleum waste is followed by the code (May Subd Geog), but no instances of geographic subdivision are printed. In this case, the specific rules for geographic subdivision in the Manual must be consulted in order to construct a subject heading with geographic subdivision correctly. Those geographic subdivisions that are printed are usually required so that references to narrower headings may lead from the topic in a special place to an instance of that topic. For example, many geographic subdivisions are printed under the heading Rivers (May Subd Geog) so that references may lead to the names of individual rivers.

Geographic Subdivision and Place Names Divided by Topic

The expression of geographic place in relation to a topic is handled in two different ways in LCSH. Topical subject headings can be subdivided by place, as in Labor supply— France, or geographic headings may be subdivided by topic, as in Massachusetts—History. Since a general rule does not exist that explains under which circumstances one method is preferred to the other, it is best to rely on instructions under the specific subject headings to determine which method is used. If a subject heading contains the designation (May Subd Geog), a geographic place is brought out by subdivision. For example, Labor supply (May Subd Geog) means that place will follow the subject, as in Labor supply—France. If, however, the heading lacks the instruction or specifically states (Not Subd Geog) and there is a general reference to a specific subdivision under names of places, then the specific geographic area precedes the topic. For example,

  SA subdivision History under names of countries, cities, etc., and individual corporate bodies, uniform titles of sacred works, classes of persons, ethnic groups and topical headings

authorizes the construction of the combination Massachusetts— History.

The use of subdivisions under names of places is more problematic because it is necessary to refer to the Manual for a complete listing of these subdivisions. No single place name lists all of the available subdivisions. The subdivisions under the headings France, Great Britain, and United States in LCSH are representative of some of the subdivisions that may be used. However, date subdivisions that represent historical periods must be established uniquely under each place name.

Free-floating Subdivisions

Until 1974, subject catalogers normally established specific heading-and-subdivision combinations for printing in LCSH. In 1974 it was decided that many subdivisions of subject headings would in the future be constructed according to rules instead of according to specific authorization, and the term free- floating subdivision was coined. Because authority records have seldom been prepared for these combinations since 1974, the resulting combinations infrequently appear in LCSH. Therefore, those subdivisions that do appear are either remnants from earlier days or subdivisions needed so that narrower headings or previously used headings can be shown.

Subject heading strings, made up of established headings and free-floating subdivision combinations, are assembled in building-block fashion by the cataloger at the time of assigning subject headings to a work being cataloged. Most subdivisions are accessible in LCSH itself either through a general see also (SA) reference under the heading that is the same as a subdivision (for example, Abstracts), or through a general USE reference (for example, Ability testing). In addition, guidelines for the use of many subdivisions appear in the notes and references under the corresponding generic headings or references in the text of LCSH. In addition, catalogers should refer to various lists and instruction sheets in the Manual in order to combine elements correctly. For a complete list of the free-floating subdivisions in use as of January 2018, as well as guidelines for their use, see the section “Free-floating Subdivisions” in this 40th edition of LCSH.


In 1974 the principle of free-floating subdivisions controlled by pattern headings was officially incorporated into LCSH. Standardized sets of topical and form subdivisions were developed for use under particular categories of subject headings or name headings used as subjects. To avoid repeating these subdivisions under all possible headings, only one or a few representative headings from each category are printed in LCSH with a set of the subdivisions appropriate for use under other headings belonging to the category. Such headings are called pattern headings for the respective categories.

Because many subdivisions now authorized as free- floating by a pattern heading were printed in LCSH before 1974, they still appear in numerous instances under individual headings belonging to a category. Some headings incorporating subdivisions controlled by pattern headings are needed to provide the reference structure for other headings.

General free-floating subdivisions are not usually printed in LCSH under pattern headings. However, some general free floating topical and form subdivisions are listed under pattern headings if they represent an important topic or type of material pertinent to the category, or if they are cited as examples in general see also references.

Any subdivision established under a pattern heading is usable, if appropriate and no conflict exists, under any other heading belonging to its category. Within these specified limits, it is a free-floating subdivision.

For example, a set of subdivisions has been developed for organs and regions of the body. Typical headings belonging to this category include Alimentary canal, Autonomic ganglia, Renal artery, Toes, etc. There are two pattern headings for parts of the body: Foot and Heart. The subdivisions established under either of these headings may be used as free-floating subdivisions under any heading belonging to the category if it is appropriate. To illustrate, the heading Joints—Biopsy is not printed in LCSH. It is nonetheless a valid heading because the subdivision —Biopsy appears under Heart.

Additional information on pattern headings is found in the Manual. Types of headings included in the categories are described there. Lists of the subdivisions that can be used under other headings belonging to the category are also provided. When new subdivisions are added to the pattern headings, the subdivisions are printed under the pattern headings in LCSH.

The table of pattern headings is arranged alphabetically by category of headings covered by pattern headings; the specific headings under which the subdivisions will appear in LCSH are listed in the right-hand column.

LCSH table of pattern heading


LCSH is primarily a listing of topical subject headings. Ever since the first edition, names of persons and names of corporate bodies (jurisdictions, companies, etc.) have been omitted from the list unless needed as patterns or examples, or unless a subdivision must be printed. In addition, the list in the past omitted some of the topical headings established and assigned as subject headings to bibliographic records by the Library of Congress. Although certain categories of headings were established and applied to works cataloged, they were omitted from the printed list in order to save space.

In 1976 the decision was made to print the following types of formerly omitted headings: names of sacred books; names of families, dynasties, and royal houses; gods; legendary and fictitious characters; works of art; biological names; and chemicals. Headings in these categories appear in the list if they were established after 1976. In 1976 the Library also began to print several other categories of formerly omitted headings: geographic regions and features; city sections; archaeological sites; extinct cities; structures; buildings; roads; parks and reserves; plazas; streets; and other proper names not usually capable of authorship. The list also contains an artificial structure called a “multiple,” of which Subject headings— Aeronautics, [Education, Latin America, Law, etc.] and Civil rights—Religious aspects—Buddhism, [Christianity, etc.] are examples. These multiple subdivisions are intended to indicate that analogous subdivisions may be used as needed without a specific authority record. That is, under the heading Civil rights—Religious aspects the name of any religion may be assigned as a further subdivision.


Four categories of headings are omitted from the list: headings that appear in the Name Authority File, free-floating phrase headings, certain music headings, and machine-generated validation records.

Headings Residing in the Name Authority File

Personal names, corporate bodies, names of jurisdictions, names of meetings, conferences, and other organized events, such as competitions and sports events, and uniform titles are omitted from the subject headings list unless used as a pattern or example, or unless a subdivision or special instruction must be printed.

In 2013 the decision was made to discontinue establishing several types of headings in LCSH: names of individual fictitious characters, legendary characters, and mythological figures; names of individual deities; and individually named animals. The headings are now established in the name authority file, and existing subject headings are gradually being cancelled in favor of the name authority records. To find the established forms of headings that do not appear in LCSH consult the online file of name authority records. For more information, consult the Manual.

Free-floating Phrase Headings

These headings are not established by subject catalogers but are composed and applied as needed
without the creation of an authority record. These headings are:

[Name of city] Metropolitan Area ([Geographic qualifier])

[Name of city] Region ([Geographic qualifier])

[Name of city] Suburban Area ([Geographic qualifier])

[Name of river] Region ([Geographic qualifier])

[Name of geographic feature] Region ([Geographic qualifier])

Establishing and Printing Certain Music Headings 

Although a large number of existing music headings have been printed in LCSH when specific cross-references are not needed, LC does not print headings with qualifiers specifying instruments or vocal parts when the main heading has a general scope note, with or without a general see also reference. 

Machine-generated validation records 

In 2007 the Policy and Standards Division began to create and distribute subject authority records that were machine-generated from subject headings residing in bibliographic records in the Library’s files. These strings typically include a topical subject heading followed by a geographic, topical, or form subdivision. Validation records are distributed to subscribers of the MARC 21 subject authority records via Internet FTP on a weekly basis along with the subject authority headings that appear in these volumes. There were 78,565 validation records as of January 2018. 

For more specific instructions, consult the Manual


Filing rules that provide for efficient arrangement of bibliographic entries by computer have been followed. These rules (Library of Congress Filing Rules, 1980) are also used in other Library of Congress computer-generated bibliographic products.

The basic principle is to file a heading strictly as expressed in its written form, word by word. A word is defined as consisting of one or more letters or numerals set off by spaces or marks of significant punctuation, such as the hyphen. Therefore, abbreviations, acronyms, and initials without interior punctuation (e.g., Dr., ALGOL, IBM) are filed as words. Initials separated by punctuation are filed as separate words at the beginning of their alphabetic group.

C-coefficient, USE Clebsch-Gordan coefficients
C.F. & I. clause, USE C.I.F. clause
C.O.D. shipments 
Ca Gaba Indians, USE Kagaba Indians
Cazcan Indians 
CCPM test, USE Constant-choice perceptual maze test
Crystals CTD (Injuries), USE Overuse injuries 

Modified letters with diacritics are filed with their unmodified equivalents. 

Möbius function 
Moeller family 
Molds (Fungi) 
Möller family, USE Moeller family

Numbers that are expressed in digits, both Arabic and Roman, precede alphabetic characters and are arranged in increasing numeric value.

4–H clubs 
14 Ranch (Wyo.) 
35mm cameras 
1939 A.D. USE Nineteen thirty-nine, A.D.
6502 (Microprocessor) 
A–5 rocket 
A.C. automobile 
A priori 
Aamand family 
Four-day week 
Nineteen thirty-nine, A.D. 
P–40 (Fighter plane) 
p-adic numbers 
P–STAT (Computer system) 
Paavola family 
Pac-Man (Game) 
Pacific Coast (Peru) 
PADIS (Information retrieval system) 
PC–1500 (Computer) 

In a chronological file, dates are arranged according to proper chronology. The word “To” is treated as if it were 0 (zero). In a chronological progression the shortest period is filed first. Period subdivisions are arranged chronologically even when the dates do not appear first. If two spans begin with the same date, the shorter time period files first:

Great Britain—History—To 55 B.C. 
Great Britain—History—To 449 
Great Britain—History—To 1066 
Great Britain—History—To 1485 
Great Britain—History—Anglo-Saxon period, 449–1066 
Great Britain—History—Edward, the Confessor, 1042–1066 
Great Britain—History—William I, 1066–1087 
Great Britain—History—Norman period, 1066–1154 Great Britain—History—1066–1687 

Inverted headings file ahead of headings with parenthetical qualification: 

Children, Maori 
Children (International law) 
Children (Roman law) 

In any subject heading, subordinate elements that follow a dash are grouped in the following order:
(a) period subdivisions, arranged chronologically
(b) form and topical subdivisions, arranged alphabetically
(c) geographic subdivisions, arranged alphabetically 

These sequences are maintained at every level of subject subdivision. 

United States—Foreign relations—20th century 
United States—Foreign relations—1945–1989 
United States—Foreign relations—Executive agreements 
United States—Foreign relations—Treaties 
United States—Foreign relations—Iran 
United States—Foreign relations—Latin America 

The filing rules require that certain entries, usually personal and corporate entries with titles, follow an unsubdivided heading and precede that heading with subdivisions. This will result in filing sequences as follows: 

Bible. English 
Bible. Matthew 

Shakespeare,William, 1564–1616 
Shakespeare,William, 1564–1616. Hamlet 
Shakespeare, William, 1564–1616—Acting see Shakespeare. . . . 

United States 
United States. Declaration of Independence—Signers 
United States—Antiquities 
United States—Territories and possessions 
United States. Air Force 

It is necessary to consult the unsubdivided heading preceding the author/title combination because it may contain information essential to understanding how the heading operates, such as whether it may be divided by place. 


Examples based on Library of Congress Subject Headings (LCSH) following principles of assigning subject headings as described in Subject Headings Manual of Library of Congress:

English literature—20th century—History and criticism.
Construction industry—United States.
India—History—Autonomy and independence movements.
Piano music (Jazz)—France—History.
Aging—Egypt—Psychological aspects.
Resource description & access--Handbooks, manuals, etc. 

Following is an example of LCSH heading “Hotels” from Library of Congress Linked Data Service:

Hotels, taverns, etc.
Broader Terms
Hospitality industry
Narrower Terms
All-suite hotels
Allergen-free accommodations
Bed and breakfast accommodations
Gay accommodations
Haunted hotels
Historic hotels
Hotel chains
Hotel lobbies
Imaginary hotels
Nonsmoking accommodations
Park lodging facilities
Safari lodges
Single-room occupancy hotels
Tourist camps, hostels, etc
Related Terms
Taverns (Inns)
Earlier Established Forms
Hotels, taverns, etc.
LC Classification

Please refer to our article Cataloging Examples which will include examples of LCSH headings in a catalog record.


Assigning and Constructing Library of Congress Subject Headings (LCSH): Principles, Practices, and Examples From Subject Headings Manual (SHM) Instruction Sheet H 180


1. General rule (how-to assign Library of Congress Subject Headings (LCSH) to the work being cataloged)

2. Cataloging treatment (how-to assign Library of Congress Subject Headings (LCSH) corresponding to the cataloging treatment of the work)

3. Number of headings (what is the number of Library of Congress Subject Headings (LCSH) required in a catalog record)

4. Specificity (in assigning Library of Congress Subject Headings (LCSH))

5. Depth of indexing (how-to assign Library of Congress Subject Headings (LCSH) that most closely correspond to the overall coverage of the work)

6. General topic and subtopic; principle vs. specific case (how-to assign Library of Congress Subject Headings (LCSH) if a work discusses a general topic with emphasis on a particular subtopic, or presents a principle and illustrates the principle with a specific case or example)

7. Two or three related headings (how-to assign Library of Congress Subject Headings (LCSH) if a heading exists, or can be established, that represents the two or three topics discussed in a work)

8. Rule of three (when it is appropriate to assign up-to three Library of Congress Subject Headings (LCSH))

9. Rule of four (when it is appropriate to assign up-to four Library of Congress Subject Headings (LCSH))

10. Multi-element topics (How-to assign Library of Congress Subject Headings (LCSH) if a work discusses a complex or compound topic for which a single heading neither exists nor can be practically constructed or established)

11. Additional aspects (How-to assign Library of Congress Subject Headings (LCSH) with important additional aspects, such as limitation to a specific place or time, focus on specific named entities, and presentation in a particular form)

12. Concepts in titles (How-to assign Library of Congress Subject Headings (LCSH) to bring out concepts in titles and subtitles)

13. Additional headings (How-to assign additional Library of Congress Subject Headings (LCSH) which are required because of the complex nature of certain topics, or special practices that have been developed for particular topics)

14. Objectivity (Principle to avoid assigning Library of Congress Subject Headings (LCSH) that label topics or express personal value judgments regarding topics or materials)

15. Constructing headings (Examples of different types of Library of Congress Subject Headings (LCSH))

16. Complete subject heading strings with subdivisions (Addition of subdivisions to Library of Congress Subject Headings (LCSH) to complete subject heading strings)


Twenty-percent rule is an instruction in the Library of Congress Subject Headings (LCSH) that states to assign headings only for topics that comprise at least 20% of the resource. LCSH headings assignment guidelines and examples are given below in the light of LCSH 20% rule. When subject cataloging follow these instructions to select the most appropriate subject headings for your catalog record. As a general rule in LCSH, the cataloger should assign to the work being cataloged one or more subject headings that best summarize the overall contents of the work and provide access to its most important topics. But LC practice according to this instruction restricts the assignment of headings only for topics that encompass 20% or more of a resource. 20% rule can be very helpful in keeping the subject headings focused on the major topical components of a work. The twenty-percent rule may also apply to supplemental content or notable bibliographic features, such as bibliographies, maps, images, and so on. In the case of a work containing separate parts, for example, a narrative text plus an extensive bibliography or a section of maps, or a book with accompanying materials, such as a computer disc, assign separate headings for the individual parts or materials if they constitute at least 20% of the item and are judged to be significant. To know more see main article: Twenty-Percent Rule (LCSH)


  • “Multiple” Subdivisions to be Cancelled from Library of Congress Subject Headings [November 7, 2018] - In order to better support linked-data initiatives, the Library of Congress’ Policy and Standards Division will cancel “multiple” subdivisions from Library of Congress Subject Headings (LCSH) beginning in December 2018. A multiple subdivision is a special type of subdivision that automatically gives free-floating status to analogous subdivisions used under the same heading. In the example Computers—Religious aspects—Buddhism, [Christianity, etc.], the multiple subdivision is —Buddhism, [Christianity, etc.]. Staff in PSD will cancel the multiple subdivisions from LCSH and create individual authority records for each valid, complete, heading string that was created based on a multiple subdivision.  PSD wishes to be as comprehensive as possible when making authority records based on heading strings used in bibliographic records; OCLC Research will assist in this effort by providing to PSD lists of the headings used in bibliographic records in OCLC. To know more see main article: “Multiple” Subdivisions to be Cancelled from Library of Congress Subject Headings

  • Cancellation of multiple subdivisions in LCSH [July 17, 2020] 
    • Cancellation of multiple subdivisions used after [name of person]–Characters in the Library of Congress Subject Headings (LCSH)
    • Cancellation of the multiple subdivisions –Religious aspects—Baptists, [Catholic Church, etc.] and –Religious aspects—Buddhism, [Christianity, etc.]
    • To know more see main article: Cancellation of multiple subdivisions in LCSH


Library of Congress Subject Headings (LCSH) Authority Record
Library of Congress Subject Headings (LCSH)  - Subject Authority Record


LCSH Quiz -- List of questions, answers, and quizzes on Library of Congress Subject Headings (LCSH) from Library and Information Science Questions Answers Quizzes. Please visit this collection and locate questions given below under the heading "Unit V - Information and Knowledge Organization and Management" where you will also find their URLs having answers and further explanations.
  • Complete Cutter's "objects" of the catalog. Fill in the Blanks. To enable a person to ________ a resource of which the ________, title, or ________ is known. To show what the library has by a given ________, on a given ________, or in a given ________ of literature.
  • Metadata can be defined as [Fill in the Blanks. Metadata can be defined as ______ about ______. In libraries, the creation of metadata is often referred to as ______. It is a subset of ______ organization.]
  • Metadata is structured information that describes resources [True or False]
  • What are the two primary methods of subject access?
  • Using a controlled vocabulary is the same as using natural language. [True or False]
  • What are the purposes of a controlled vocabulary? (Select all that apply.) [A) To allow for consistent retrieval of resources. B) To allow for comprehensive searching of a catalog. C) To allow user-supplied tags that are specific to the user that applies them. D) To allow for the control of synonyms. E) To link terms that are related to each other, for ease of retrieval. F) To repeat all the nouns that appear in the titles of every resource.]
  • Keywords and social tagging are [Fill-In-The-Blank: Keywords and social tagging are ______ approaches to access. They provide ______ collocation for resources.]
  • A simple term list (a "pick list") _____ semantic relationships among terms [(A) does not show (B) shows]


Here we are providing a list of tools and resources for the use of Library of Congress Subject Headings (LCSH).

Five services provide information about new and revised headings. First, a distribution service supplies the subject headings in the MARC 21 authorities format via Internet FTP on a weekly basis to supplement the master database file of subject authority records. Second, L.C. Subject Headings Monthly Lists are a timely source of information about new and changed subject headings, class numbers, references and scope notes. The lists are posted monthly to the World Wide Web at Third, Classification Web provides World Wide Web access to Library of Congress Subject Headings and Library of Congress Classification to subscribers. Fourth, subject authority records are included in the Library’s Web authorities service and may be searched and viewed at Fifth, subject authorities are freely available for searching and download through the Library’s Linked Data Service at


Videos on Library of Congress Subject Headings (LCSH) from the article Library and Information Science Videos. These videos are in the form of a playlist created in the YouTube channel of Librarianship Studies & Information Technology. Just click on the top-left side of the video player to get the list of videos in the playlist from where you can choose the desired video to watch.


Main article: Controversies in the Library of Congress Subject Headings (LCSH): the Case of Illegal Aliens

Crystal Vaughan in her article The Language of Cataloguing: Deconstructing and Decolonizing Systems of Organization in Libraries⁶ writes: "As society, politics, and economies change, so too does the language of representation. Therefore, the Library of Congress subject headings (LCSH) as a system of categorization is only as effective as the language that is used to define what is and what is not. Moreover, those who control the language of categorization control access to the information categorized within that system. Consequently, librarians must always be critical of the language they are using in their information organization systems. Language is continuously evolving according to societal discourse and politics; therefore, if libraries are to maintain their social responsibility to provide information to all, including socially disadvantaged and marginalized peoples, then librarians must continuously advocate for changes to subject headings. Librarians must also recognize and reflect on their own internal biases when cataloguing and make it their job to deconstruct language and decolonize the systems that perpetuate the continued marginalization of others ...  Despite the many changes that have been implemented in the LCSH, there are still many LCSH that marginalize and dehumanize vulnerable, disadvantaged, and/or minority populations, which therefore restricts their access to information. If libraries are to maintain their social responsibility to provide information to all, including socially disadvantaged and marginalized peoples (IFLA, 2012)⁷, then librarians must continue to advocate for changes to politically charged or controversial subject headings. "

Here we are giving a description of some controversial LCSH headings who are considered pejorative or biased by some people.


The LCSH heading "Blacks" is considered disrespectful by some.

Illegal aliens

“Illegal aliens” is a controversial LCSH heading that is used for undocumented immigrant persons who are not citizens of the country in which they reside.

For many years, the Library of Congress categorized many of its books under a controversial subject heading: “Illegal aliens.”⁴

Screenshots of the heading Illegal aliens in LCSH from the Library of Congress Website

LCSH heading - Illegal aliens
LCSH heading - Illegal aliens [Source: Library of Congress Authorities]

LCSH heading - Illegal aliens
LCSH heading - Illegal aliens [Source: Library of Congress Linked Data Service]


In 2013, Dartmouth undergraduate and former undocumented immigrant, Melissa Padilla, came across the current LCSH “Illegal aliens” while doing research. Angered, Padilla stated the term is essentially used to “criminalize the choices our parents made in order to provide us with better lives,” and is meant to demean Mexican immigrants specifically. Padilla brought up the issue with Dartmouth students at a meeting of the Coalition for Immigration Reform, Equality and Dreamers, which, with the help of Dartmouth librarians, submitted a formal request to LC in 2014 to replace the term “Illegal aliens” with “Undocumented immigrants.” In February 2015, LC publicly responded that it would not change the heading. Following discussions in ALA including within the Subject Analysis Committee (SAC), Social Responsibilities Roundtable, and REFORMA, ALA formulated a resolution asking LC to reconsider the original request, arguing that “aliens” and “Illegal aliens” are pejorative terms.⁸

In 2016, the Library of Congress announced that it would reconsider the usage of “Aliens” and its related terms in the Library of Congress Subject Headings, following a student-led movement to change the pejorative term “Illegal Aliens.” Yet, three years on, these terms remain in the LCSH.⁵

On March 22, 2016, the library made a momentous decision, announcing that it was canceling the subject heading “Illegal aliens” in favor of “Noncitizens” and “Unauthorized immigration.”

However, the decision was overturned a few months later, when the House of Representatives ordered the library to continue using the term “illegal alien.” They said they decided this in order to duplicate the language of federal laws written by Congress.

This was the first time Congress ever intervened over a Library of Congress subject heading change. Even though many librarians and the American Library Association opposed Congress’s decision, “Illegal aliens” remains the authorized subject heading today.

Cataloging and classification are critical to any library. Without them, finding materials would be impossible. However, there are biases that can result in patrons not getting the materials they need.

Change the Subject - a Documentary

The project

Change the Subject shares the story of a group of college students, who from their first days at Dartmouth College, were committed to advancing and promoting the rights and dignity of undocumented peoples.  In partnership with staff at Dartmouth, these students – now alumni – produced a film to capture their singular effort at confronting an instance of anti-immigrant sentiment in their library catalog.  Their advocacy took them all the way from Baker-Berry Library to the halls of Congress, showing how an instance of campus activism entered the national spotlight, and how a cataloging term became a flashpoint in the immigration debate on Capitol Hill.

Year: 2019
Runtime: 54 minutes
Language: English
Country: United States

Change the Subject - Trailer


Check out the following headings. We were surprised to find them in the LCSH.

Chess for the blind


Even after all the criticisms, LCSH is the most used subject headings list in libraries all around the world. Its usage and adoption by libraries has been increased by leaps and bounds since it is made available free by the Library of Congress. It remains a model for many other vocabularies in English and other languages. The strongest aspect of LCSH is that it represents subject headings of the Library of Congress, the national library of the United States, one of the richest of national libraries of the world. The administrative and managerial machinery of LC has made it possible for LCSH to stand out as an undisputed leader.

  • LCSH
  • LC Subject Headings
  • Library of Congress Subject Heading



1. Library of Congress, "LCSH Introduction," (accessed February 22, 2019).

2. Janis L. Young and  Daniel N. Joudrey, Library of Congress, "Library of Congress Subject Headings: Online Training," (accessed March 17, 2020).

3. Dartmouth College, "Change the Subject," (accessed April 1, 2020).

4. Amanda Ros, The Conversation, "The bias hiding in your library," (accessed April 1, 2020).

5. Grace Lo, "“Aliens” vs. Catalogers: Bias in the Library of Congress Subject Heading," Legal Reference Services Quarterly, 38, no. 4 (2019) (accessed April 1, 2020).

6. Crystal Vaughan, "The Language of Cataloguing: Deconstructing and Decolonizing Systems of Organization in Libraries," DJIM, 14 (2018). 

7. International Federation of Library Associations and Institutions (IFLA).(2012, August). IFLA code of ethics for librarians and other information workers (full version). Retrieved from

8. Providing alternative subject headings for controversial Library of Congress subject headings in the Alliance shared ILS: Discussion paper by the Alliance Cataloging Standing Group


Article Title
  • Library of Congress Subject Headings (LCSH)

Website Name
  • Librarianship Studies & Information Technology


Last Updated
  • 2020-04-01

Original Published Date
  • 2017-12-20

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