This document summarizes several studies conducted by Beth Picknally Camden at the University of Pennsylvania Libraries. The first study examined the fast-track replacement process for missing books and found that about half of sampled replacements were no longer missing. Replacement copies circulated less than original copies. A second study looked at the cost and value of periodical check-in and found through surveys that patrons rarely had questions about current issues. A third study analyzed the costs and activity of returning books to vendors for approval plans and found declining return rates over three years.