When multiple formats of the same book are available, to what extent does use of one format impact use of the other? Are there similar patterns of use that might predict preferences for a particular format? This study analyzes three years worth of use data for a large e-book collection in comparison with circulation data for the same set of titles. Using COUNTER data, more nuanced publisher-supplied data, and ILS circulation statistics, we examine usage from multiple angles to show both overlap and degree of usage. In addition to presenting detailed use data, we will discuss the methodology used to gather and compare these large data sets. This study will help determine whether there are similarities in use level for the different formats, helping us learn more about user preferences, and helping us build better collections.