This study compares three influential controlled-vocabulary systems—Sears List of Subject Headings, Library of Congress Subject Headings (LCSH), and Medical Subject Headings (MeSH)—through a comparative analytical framework centred on subject access, semantic relationships, specificity, hierarchy, syndetic structure, and knowledge organization. A coded secondary dataset of 90 heading records was constructed, comprising 30 legally traceable public Sears headings, 30 LCSH headings, and 30 MeSH descriptors. Each entry was coded for scope-note availability, broader-term, narrower-term and related-term relationships, entry-term richness, hierarchy level, coordination tendency, specificity, user-access support, and cross-reference richness. Descriptive statistics, chi-square testing, Kruskal–Wallis comparison, and Spearman correlation were used to interpret cross-system differences. The results show a graded movement from Sears as a compact, user-facing general subject-heading list, to LCSH as a large-scale national authority vocabulary with strong pre-coordination, and to MeSH as a domain thesaurus optimized for biomedical indexing, hierarchical explosion, and post-coordinate retrieval. Scope-note availability differed significantly by system, and specificity scores also varied significantly across the three vocabularies. Synonym and entry-term richness showed a strong positive association with coded user-access support. The discussion locates these empirical findings within Dr. M. P. Satija’s contributions to subject heading theory, especially his emphasis on aboutness, specificity, terminological control, classification discipline, and local adaptation. The study concludes that controlled vocabularies remain essential in digital discovery environments, provided that their authority structures are made transparent, inclusive, machine-actionable, and responsive to domain-specific retrieval needs.

Keywords: controlled vocabulary; subject headings; Sears List of Subject Headings; LCSH; MeSH; knowledge organization