Two types of heuristic capacity control policies a·re evaluated with a SLAM simulation model of a materials requirements planning production system. The control policy decisions are based solely on the size of the queue, as measured in standard hours of work, at each work center in the production system. Several classes of product mixes and product structures are investigated, as well as several levels of the control parameters of each control policy. The results indicate that each control policy gives rise to a unique population of weekly labor, work in process, and inventory level. Product structure is also identified as a major variable in Materials Requirements Planning systems performance. Sensitivity analysis of the cost functions for each policy indicate the conditions under which it will minimize the sum of labor costs, work in process holding costs, and inventory holding costs. The simulation model, MRPSIM, is included with a user's guide. / M.S.