The purpose of this study is to identify users of Pennsylvania public libraries and determine their reasons for using the library. In addition, the study provides information describing the impacts and benefits to those users as a result of their contact with the public library. The objectives were to: (1) describe users in terms of their education, age, sex, and household income; (2) determine the reasons for the use of the public library; (3) understand how use of the public library is valuable or beneficial to these users; and (4) describe the role of Pennsylvania public libraries in supporting economic development at both the local and statewide level. A statewide survey of public library users, site visits to 10 libraries throughout the state, and logs of critical incidents of significant impacts provided data. The study found that there are numerous and important impacts and benefits that result from use of Pennsylvania public libraries. Appendices include: Focus Group interviews "Research Method"; "Focus Group Questions"; a participant questionnaire for library personnel and users; "Critical Impact Log Method"; a public services impact log; "Content Analysis Categories Reference Desk Critical Incident Log"; "Pennsylvania Public Library User Survey"; and survey instructions. (AEF)