In 1981 and 1982, a group of 5 organizations conducted a coordinated study of public online catalog users and nonusers in 31 research, academic, community college, public, and governmental libraries with 17 different online catalogs. It was found that: (1) the most important user characteristic linked with success and satisfaction in using online catalogs was frequent experience with the online catalog itself; (2) the kind of search being performed was also important as a determinant of success and satisfaction; (3) users adapt their search approaches to the capabilities and limitations of the online catalogs used; and (4) the form and nature of training and user assistance were important, with users who received at least some initial training and assistance showing more satisfaction and success than those who did not. This report presents a detailed data analysis of the project, covering statistical techniques employed and the findings related to users, search tasks, the online system's user interface, and the library setting. Extensive appendices provide a 25-item project bibliography, a sample user questionnaire, tables showing regression analyses for all user variables from the 4 largest academic systems (University of California, Ohio State University, Syracuse University, and Northwestern University), and bar charts with information on user variables from 13 libraries. (ESR)