This paper describes an effort at the University of Illinois at Chicago (UIC) Library to respond to user needs as they are revealed in transaction logs of catalog use. It illustrates success in improving access to catalog records through a re-engineering process. The UIC Library Re-engineering Project, the administrative structure to study transaction logs, and the resultant managerial decisions are outlined. Changes made to screen displays and to the OPAC are detailed. Focusing on customer satisfaction, UIC catalog librarians joined forces with colleagues to identify users' unmet needs and preferences through transaction log analysis. In order to minimize mismatches between users' expectations and services actually provided, UIC catalog librarians studied transaction logs and adjusted the OPAC. Specific efforts to increase access to the library's collections and the steps taken to enhance and customize bibliographic and authority records are detailed. Transaction log analysis has enabled UIC to alter the form and content of its OPAC to fit the changing needs of diverse and widely dispersed users. While maximizing dwindling resources, we have been able to deliver an improved, reengineered product to our customers. UIC catalog librarians will continue to be mindful of user needs as we create, modify and maintain data in the constantly evolving OPAC.