The specific goal of this project is to examine and compare how library users access, use, and interact with two social discovery systems used in two Canadian public library systems. Transaction log analysis will be conducted to answer the following research questions: a) How do public library users interact with social discovery systems? Specifically, which enhanced catalogue features do they use, e.g., faceted navigation, user-contributed content such as tagging, reviews, and ratings, sorting features, etc., and with which frequency? b) How does usage between the two social discovery systems compare? Specifically, are there commonalities or differences between how public library users use different social discovery systems? and c) Does the use of social discovery systems change over time? Specifically, is the use of the features in social discovery systems consistent over time?