This review takes a critical approach in summarizing and evaluating the methodology and scope of catalog use studies, with emphasis on the subject approach to card catalog searching. Subject access is defined in this report; however, the process of subject searching, described repeatedly in library literature, has been based upon common sense understanding rather than systematic observation. The findings of catalog use studies are classified into: (1) generalizations on the physical format of the catalog, information found on the cards, catalog searchers' educational level or area of expertise, and reference assistance; (2) generalizations specific to subject searches, user characteristics, and the physical structure of the catalog; and (3) generalizations specific to known-item searches and nonstandard information, failure at the catalog, and author-title information. The major reviews of catalog use studies and their methods are also covered. A bibliography of catalog use studies and a cited author index are provided. (Author/RAA)