Researchers at American University investigated user preferences for discovery layer features, interface design, and content. They tested local implementations of WorldCat Local and Aquabrowser by conducting a group test with eighteen students and individual tests with ten students. Students searched a given question and a topic of their choosing and talked about their experiences. The group usability session yielded preliminary findings and informed the individual tests. Using the constant comparative method, the researchers coded qualitative data collected during the individual tests and grouped participant preferences into three primary categories: functionality, interface display, and content. Findings revealed that underclassmen tended to prefer WorldCat Local, while upperclassmen and graduates tended to prefer Aquabrowser. Participants most preferred the following features: links to full-text articles using a link resolver, results incorporating both articles and books, and facets like date, format, and subject. They viewed word clouds, the ability to search libraries beyond the local library or consortium, and user-generated reviews as optional rather than required features. While one system did not emerge as the preferred system, understanding their preferences informed the decision to implement Summon as the permanent discovery layer for the Library and determined configuration options for the new system. Other libraries may benefit from the coding system developed during the study and the methodology for testing potential systems with users. (Contains 2 tables, 4 figures, and 1 note.)