Many academic libraries have liaison programs as a means of building relevant and useful library collections and to promote library resources to campus users. Librarians have long served as liaisons without the benefit of much data to guide decisions. In this age of library budget cuts, librarians need to make every dollar count. What collection and use data help liaisons build a quality monograph collection that better meets the needs of library users? This article offers some ideas for providing the data needed by liaisons for more informed decision making and collection management and, ultimately, for ensuring that library materials purchased are needed and used.