As one of ebrary’s largest academic library DDA customers, the program at the University of Iowa Libraries has been highly successful, though not without challenges. This presentation will present detailed findings from analyzing Iowa’s demand-driven acquisition e-book usage data from over 5,000 titles purchased over 4 years, including examining subject areas, prices, publishers, and other relevant metrics. This presentation will serve as update to a popular session at Charleston in 2010 (Give ‘Em What They Want: Patron-Driven Collection Development), where the University of Iowa Libraries presented data from a 1-year pilot program. Now, with 4 years of experience under our belts, a lot more data, and over a half-million dollars spent from our coffers, Iowa will share what we have learned, gained, and changed as a result of our experiences