Over the past several years, Utah State University Library has followed national patterns by rapidly developing our e-book collection to support the research and teaching needs of the university. In certain disciplines, however, we have been particularly aggressive, specifically, in psychology, environmental science, biology, and life sciences. These areas reflect several of the disciplinary strengths of our institution. Our question is whether or not, in the world prior to demand driven acquisitions, prospective buying of large amounts of content has had any effect on electronic collection use within disciplines. We will present an analysis of our overall e-book usage data from the past several years in order to ascertain whether our emphasis on electronic collection building in specific subject areas has resulted in a proportional increase in use in those areas. We will then compare these trends with print book use in the same subject areas, to see whether we were accurate in projecting that e-books would become the preferred format once they were more widely available. We will discuss the ways in which we have successfully changed our collection building patterns as well as areas where we can improve or where we may want to refocus our efforts. We will also share the challenges we faced in gathering and analyzing our data. Audience members will be encouraged to share their own thoughts on how to find the appropriate balance between print and e-book collection development for their institutions as well as how to think about e-book usage reports. Attendees can expect to learn about the challenges of e-collection assessment and will learn strategies that they can adapt to their own institutions.