In May 2001, after several years of planning and development, The Pennsylvania State University Libraries implemented a new integrated library system. The move from a twenty-year-old locally developed system to SIRSI Unicorn led to many changes in library operations and in the work of the library faculty and staff. It also affected our users in ways that we did not expect. A “Tell Us What You Think” button on the Libraries home page provided a convenient mechanism for users to respond to our system migration and the changes they saw in The CAT, our library catalog. Analysis of the questions and comments we received during the four months after the system migration has provided insight into user search behavior and problems with functionality and design of the catalog interface. Perhaps more importantly, the migration also provided us with an unexpected opportunity to evaluate and expand our Web-based user services.