The authors investigated quantitative methods of collection use analysis employing library data that are available in ILS and ILL systems to better understand library collection use and user needs. For the purpose of the study, the authors extracted circulation and ILL records from the library's systems using data-mining techniques. By comparing these data to records of books acquired in a four-year period, the study reveals generally good collection use as well as some unmet collection needs. The study also offers a method of compiling and sharing these multiple types of usage data among work groups to create feedback mechanisms to inform the work of selectors and suggest modifications to collection development practices.