Wednesday, January 10, 2018

Library of Congress Subject Headings (LCSH)

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, and published annually. It is popularly known by its abbreviation as LCSH and is sometimes used interchangeably with the phrase subject authority file.

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.

LCSH comprise 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 contain 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.

Library of Congress Subject Headings (LCSH) was originally developed by the Library of Congress for use in its cataloging records in 1898. It was first published in 1914 under the title Subject Headings Used in the Dictionary Catalogs of the Library of Congress. Since then, it has become the standard list for providing subject headings in the United States as well as other countries. The list has gone through many editions. Starting from the eighth edition, the title was changed to Library of Congress Subject Headings (LCSH). The thirty-seventh edition of Library of Congress Subject Headings (LCSH 37) contains headings established by the Library through January 2015. 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. Approximately 337,354 authority records were in the file then. The subject authority database from which the headings in this edition were drawn indicates that the file contains approximately 24,018 personal name headings of which 22,854 represent family names, 9,454 corporate headings, 9 meeting or conference headings, 485 uniform titles, 239, 916 topical subject headings, and 60,354 geographic subject headings. There are 770 general USE references, 4,360 general see also references, 294, 791 references from one usable heading to another, and 354, 879 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). Subject headings are proposed as needed for new cataloging, due to literary warrant--a heading must be needed to describe a work before it can be proposed for inclusion. These proposals are approved by cataloging policy specialists in the Library of Congress’ Policy and Standards Division. The specialists ensure that the proposals conform to the rules and structure of LCSH, including heading format, provision of references, and scope notes. Approved proposals become part of the online authority file of subject headings at the Library of Congress. LCSH is not complete unto itself. Names of persons and corporate bodies, jurisdictions and quasi-jurisdictional entities, and titles can generally be assigned as LC subject headings, but are established in the LC/NACO Name Authority File (NAF) according to instructions contained in RDA: Resource Description and Access (previously AACR2).

The rules for constructing and assigning LCSH heading are contained in two sources: the introduction to LCSH and the Subject Headings Manual (SHM), both available online from the Library of Congress website. Based on these guidelines LCSH has provision for the construction of pre-coordinated indexing strings including headings, plus rules for combining the single terms in strings and one or more levels of subheading. Based on these rules a subject heading may also be subdivided by the addition of form subdivisions, geographical subdivisions, chronological subdivisions, and topical subdivisions to add greater specificity. In a MARC bibliographic record Subject Heading is given in a 6XX field, consisting of either a single element in an $a subfield or of an $a subfield followed by subdivisions in $v, $x, $y, and/or $z subfields, that designates what a work is or what it is about.

The present form of LCSH is quite different from the vocabulary that was initially developed at LC over a century ago. The present LCSH has a thesaurus like syndetic structure in the form of USE references to direct the user from a synonym or quasi-synonym to the preferred term, and UF (used for), BT (broader term), RT (related term), and NT (narrower term) notes to indicate semantic relations between headings. LCSH was published in large red volumes (till recently five), which were typically displayed in the reference sections of libraries and in cataloging departments. In early 2013, the Library of Congress announced that it is transitioning to online-only publication of its cataloging documentation. The printing of documentation for purchase has now ceased, and all new editions and updates will be freely available as PDF files on LC’s website. The final printed edition of LCSH was the 35th, published in 2013. The 37th edition is issued in January 2015 as PDF files that may be freely downloaded from PSD plans to issue new PDF editions annually. LCSH may also be searched online in the Library of Congress Classification Web, a subscription service, or free of charge (as individual records) at Library of Congress Authorities. LCSH headings can also be searched from LC Linked Data Service


1  LCSH Examples
2  LCSH Assigning and Constructing
3  LCSH Twenty-Percent Rule

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

LCSH Assigning and Constructing

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)

LCSH Twenty-Percent Rule

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)

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



  • Salman Haider


  • Last Updated: 2018-12-15
  • Written: 2017-12-20

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