This report looks at the use of public library online circulation systems for the generation of in-house secondary information--such as statistical reports and mailing lists--and also considers problems in maintaining confidentiality of patron records when using online circulation systems. Based on a survey of the literature, general information is presented on the report-generating and system security capabilities of 17 online circulation systems. More detailed information on OCLC's Circulation Control System, East Brunswick Library's Circulation System, Ringgold's Nonesuch Circulation System, the University of Toronto's UTLAS CIRC, the Geac Library Information System, and CLSI's LIBS 100, based on material provided by the vendors, is presented in an appendix. Also included in the report is a survey of the legal basis for confidentiality of patron records with a discussion of cases where confidentiality has been challenged under state open-record laws. Finally, based on responses to a questionnaire, information is presented on the uses and problems of online circulation systems in actual library situations, specifically in the Albany Public Library (New York), the Liverpool Public Library (New York), and the Milwaukee Public Library (Wisconsin). A 46-item annotated bibliography and a subject index to the bibliography conclude the report. (Author/ESR)