Library of Congress Subject Headings

The Library of Congress Subject Headings (LCSH) comprise a thesaurus (in the information science sense, a controlled vocabulary) of subject headings, maintained by the United States Library of Congress, for use in bibliographic records. LC Subject Headings are an integral part of bibliographic control, which is the function by which libraries collect, organize, and disseminate documents. It first appeared in 1898, a year after the publication of Library of Congress Classification (1897). The last print edition was published in 2016 and access to the continuously revised vocabulary is now available via subscription and free services. Subject headings are normally applied to every item within a library's collection and facilitate a user's access to items in the catalog that pertain to similar subject matter. If users could only locate items by 'title' or other descriptive fields, such as 'author' or 'publisher', they would have to expend significant time searching for items of related subject matter, and undoubtedly miss locating many items because of the ineffective and inefficient search capability.

An art and a scienceEdit

Subject heading is a human and intellectual endeavor, where trained professionals apply topic descriptions to items in their collections. Without a uniform standard, each library might choose to categorize the subject matter of their items differently. The widespread use and acceptance of the Library of Congress Subject Headings facilitates the uniform access and retrieval of items in libraries across the world using the same search strategy and LCSH thesaurus, if the correct headings have been applied to the item by the library. Some LCSH decisions involve a great amount of debate and even controversy in the library community.

LCSH is the world's most widely used subject vocabulary.[1] Despite LCSH's wide-ranging and comprehensive scope, libraries that deal with more specific types of collections or user communities may use other vocabularies; for example, many medical libraries in the United States use the National Library of Medicine's Medical Subject Headings. In Canada, the National Library of Canada worked with LCSH representatives to create a complementary set of Canadian Subject Headings (CSH) to express the topic content of documents on Canada and Canadian topics.

LCSH policy issuesEdit

Historically, issues have revolved around the terms employed to describe racial or ethnic groups. Notable has been the terms used to describe African-Americans. Until the 1990s, the LCSH administrators had a strict policy of not changing terms for a subject category. This was enforced to tighten and eliminate the duplication or confusion that might arise if subject headings were changed. Therefore, one term to describe African-American topics in LCSH was 'Afro-American' long after that term lost currency and acceptance in the population. LCSH decided to allow some alteration of terms in 1996 to better reflect the needs and access of library users. Nevertheless, many common terms, or 'natural language' terms are not used in LCSH, and may in effect limit the ability for users to locate items. There is a growing tradition of research in Library and Information Science faculties about the cultural and gender biases that affect the terms used in LCSH, which in turn may limit or deprive library users access to information stored and disseminated in collections. LCSH became the topic of news coverage across the U.S. in 2016 when The Library of Congress decided to revise the heading 'Illegal aliens' and was the subject of opposition from congressional Republicans.[2][3]

Sanford Berman, a notable American science scholar on this subject, has also pointed out the difficulty in finding material on certain topics, such as various denialisms, because the natural language terms for them, climate change denialism, for example, have not been incorporated into LCSH.[4]

Criticism has also arisen regarding the biased organization and description of materials on sexuality. Works about heterosexuality are scarcely labeled as such in LCSH, giving users the impression that only queer sexuality deserves examination because heterosexuality is the norm.[5]

Data accessEdit

The Subject Headings were formerly published in large red volumes (currently ten), which are typically displayed in the reference sections of research libraries. They are also accessed online in the Library of Congress Classification Web, a subscription service, or free of charge (as individual records) at Library of Congress Authorities. The Library of Congress adds new headings and revisions to LCSH each month.[6]

A web service,, was set up by Ed Summers, a Library of Congress employee, circa April 2008,[7] using SKOS to allow for simple browsing of the subject headings. was shut down by the Library of Congress's order on December 18, 2008.[8] This announcement was met with great dismay from the library science and semantic web communities, e.g. Tim Berners-Lee[9] and Tim Spalding of LibraryThing.[10] After some delay, the Library did set up its own web service for LCSH browsing at in April 2009.[11]

Using LCSHEdit

Timothy Binga, Director of Libraries at the Center for Inquiry, notes issues that make it more difficult to use the standardized language of LCSH to find material. These include systems that allow patrons to informally tag materials in the catalog, book creators and publishers who do their own cataloging, and the incorrect application of LCSH to controversial material.[12]

Increasingly, the use of hyperlinked, web-based Online Public Access Catalogues, or OPACs, allow users to hyperlink to a list of similar items displayed by LCSH once one item of interest is located. However, because LCSH are not necessarily expressed in natural language, many users may choose to search OPACs by keywords. Moreover, users unfamiliar with OPAC searching and LCSH, may incorrectly assume their library has no items on their desired topic, if they chose to search by 'subject' field, and the terms they entered do not strictly conform to a LCSH. For example, 'body temperature regulation' is used in place of 'thermoregulation'. Thus the easiest way to find and use LCSH is to start with a 'keyword' search and then look at the Subject Headings of a relevant item to locate other related material.

See alsoEdit


  1. ^ "Library of Congress Subject Headings (LCSH)". Librarianship Studies & Information Technology. Retrieved 9 August 2020.
  2. ^ Padilla, Steve; Rivera, Selene (3 April 2016). "Library of Congress to stop using term 'illegal alien'". Los Angeles Times. Retrieved 8 August 2020.
  3. ^ Aguilera, Jasmine. "Another Word for 'Illegal Alien' at the Library of Congress: Contentious". The New York Times. Retrieved 8 August 2020.
  4. ^ Berman, Sanford (2017). "Library Catalogs Deny Science Denial". Skeptical Inquirer. 41 (3): 8.
  5. ^ Drabinski, Emily (April 2013). "Queering the Catalog: Queer Theory and the Politics of Correction". The Library Quarterly: Information, Community, Policy. 83 (2): 97. doi:10.1086/669547. JSTOR 10.1086/669547.
  6. ^ "About the Subject Headings Approved Lists". Library of Congress. 10 August 2011. Retrieved 9 August 2020.
  7. ^ Rob Styles (2008-04-02). "SKOS, Linked Data and LCSH!". I Really Don't Know. Archived from the original on 2010-03-14. Retrieved 2010-01-12.
  8. ^ Ed Summers (2008-12-18). " " Blog Archive " uncool uris". Archived from the original on February 26, 2009. Retrieved 2010-01-12.CS1 maint: unfit URL (link)
  9. ^ "Tim Berners-Lee's comment on Uncool URIs". 2008-12-20. Archived from the original on February 26, 2009. Retrieved 2010-04-20.CS1 maint: unfit URL (link)[failed verification]
  10. ^ Tim Spalding (2008-12-22). ", RIP". Thingology. Retrieved 2010-01-12.
  11. ^ "Library of Congress Update for 2009 ALA Annual Conference, January-May, 2009 (The Library of Congress at ALA Annual Conference 2009)". Retrieved 2010-01-12. In April, 2009 the Beta version of ID.LOC.GOV with the LCSH vocabulary went live.
  12. ^ Binga, Timothy (2017). "Information Bias in Library Catalogs". Skeptical Inquirer. 41 (3): 9.

External linksEdit