Manufacturers nowadays are confronted with highly demanding customers and fierce competition. To cope with these difficult circumstances, they need to have a competitive production organism. In an assembly line operating under tight planning conditions, it is of crucial importance that the right materials are being supplied at the right time and at the right place. In automotive assembly, the need for efficient material handling is particularly great because of product customization and the shortage of space to stock all required parts at the line. This dissertation proposes a mathematical cost model for evaluating the assignment of parts to one of two material supply systems, kitting or line stocking. Case data from an automotive company in Belgium is obtained and the model is extensively tested. The results demonstrate that hybrid policies, where some parts will be kitted and others will be line stocked, are preferred to either system alone.