The University of Chicago's Joseph Regenstein Library Bookstacks Department has used process mapping and continuous improvement to successfully improve its overall operations. The most recent efforts focus on Lean manufacturing, an initiative centered on eliminating waste in manufacturing processes. The conversion of the Bookstacks Department from a reactive model to Lean thinking has produced some dramatic performance improvements. This case study will describe key principles of Lean thinking and how they have been implemented to improve shelving turnaround time. (Contains 2 figures.)