In September 2009, the University of Iowa Libraries embarked on an experiment with patron-driven acquisition (PDA) of e-books with ebrary and YBP. An e-book-only PDA plan was initiated, entirely unmediated and with instantaneous access to the content. MARC records were loaded for each title, determined by our YBP approval profile and other limitations, for a total of 12,000 PDA records. Usage, cost, subject, and publisher data were analyzed for 850 purchased PDA e-books and thousands of other ebrary subscription titles. Results indicate that PDA can be a useful and effective tool for meeting user needs and building the local collection, but the role of PDA in the library's collection management program presents challenges as well as opportunities.