Canadian Tire Pacific Associates owns and operates 21 retail stores in the lower mainland of British Columbia and a central warehouse in Burnaby. In this thesis, we formulate a single-product, single-location model of its inventory system as a first step in developing an integrated, interactive inventory control system. Specifically, we formulate a Markov chain model for a periodic review system with a deterministic lead time and lost sales. The model utilizes empirical demand data to calculate the long-run average cost of inventory for a given (s,S) policy. We then develop a heuristic that locates a "near" optimal policy quickly. The heuristic incorporates a constraint on the customer service level, makes use of an updating techniq...