Purpose: This article examines the Library of Congress Subject Headings (LCSH), which is the most used subject heading system in the world and an instance of a controlled vocabulary (CV).
Design/methodology/approach: The method used to examine the system is based on both authors’ subject knowledge in the field of information science (IS) and the subfield of knowledge organization (KO). Core concepts in this domain were examined (1) by checking if they are present or not in the system; (2) if not, by determining whether LCSH contains alternative terms useful for searching documents about the missing concept, by examining books indexed by the Library of Congress (LC); (3) by identifying the semantic relations between subject headings.
Findings: The results demonstrate fundamental problems in the logical consistency of the representation of IS and KO in LCSH.
Practical implications: The implications for CVs in general are discussed.
Originality: No previous study has used our method to examine LCSH’s coverage of IS.