With both budget dollars and buying power shrinking for academic library collections, the selection of materials is a series of crucial choices. With increases in numbers of online programs, how can we determine if what we are buying is in fact what our users need? E-reserves are an increasingly popular way to provide digital copies of course readings via an online interface. This paper reports on an analysis of items placed on e-reserve at two large, publicly-supported institutions in Michigan. An inventory of these items reveals: what types of academic materials are being used; what percentage are from the libraries' electronic or print collections or from non-library sources; and whether periodical articles placed on e-reserve are from scholarly publications. The results of this analysis will provide useful insight into collection assessment, as well as the nature of materials being used by teaching faculty in support of distance learners. (Contains 6 tables and 1 figure.)