An industrial dynamics model of a university library, developed originally to investigate the effect of library control policies, is described. The model is used to analyze the effect of two policies pro posed by the Physics Library at Purdue University. After having operated under extremely crowded con ditions for the past several years, the Physics Library will move in 1971 into new, more spacious quarters. The policies for loans from the library collection have been rather free, control over the collection has been lax, and penalties for users failing to comply with library policies have been mild. The reasoning behind these policies was that if all loaned materials were returned, sufficient shelf space was unavailable. With the space limitations removed in the new quarters, the Physics Librarian can adopt one of two general policies: Policy 1 - Closer control over the library collection, more restrictive loan policies, more staff, and longer operating hours Policy 2 - Less control over the collection with more extended loan policies and increased purchases of multiple copies. Analysis of the two policies shows that Policy 1 effects a reduction in delays in return of loaned material at the expense of incurring user dissatis faction with the library and that Policy 2 results in even higher user satisfaction than is presently experienced.