In 1981 and 1982, the Research Libraries Group (RLG) and four other organizations participated in a coordinated study of public online catalog users and nonusers. Standard, self-administered questionnaires were used to gather data from 8,094 users and 3,981 nonusers in 31 research, academic, community college, public, and governmental libraries with 17 different online catalogs. This final report presents findings and implications of data collected at three institutions: Dartmouth College, Northwestern University, and Stanford University, all members of the Association of Research Libraries (ARL). The data from these institutions are contrasted with those collected from 12 other ARL libraries. These data include uses of the public online catalogs, perceived problems, preferences for improvement, and user and nonuser characteristics. The report also presents the results of a related special study which gathered qualitative evidence in structured interviews with library staff at Dartmouth, Northwestern, and Stanford. A final chapter discusses implications of the study and notes a general patron acceptance of public online access catalogs. Appendices include a list of participating libraries and computer systems, statistical analyses of data collected, sample questionnaires, and other documents. An executive summary and 47 tables are also provided. (ESR)