The focus in this study is on evaluating scheduling policies that may be used to offer a near-perfect delivery performance for vital customers in dual resource constrained (DRC) job shop environments. Prior studies in this area have modeled shops where all orders are considered to be of equal importance, and shown that any reasonable combination of worker assignment and dispatching rules that are sensitive to the shop cost factors modeled works well. However, a recent survey indicates that shops do in fact distinguish among orders on the basis of customer identity, and that certain customers have very rigid delivery guidelines which must be adhered to in order to maintain their ongoing business. The present study models such environments, and shows that the choice of scheduling policies is not inconsequential, especially if the shop aims at providing near-perfect delivery performance to a limited set of customers. In such instances, policies for deploying workers to different departments, as well as dispatching rules that use customer identity based information outperform their counterparts that are not sensitive to orders placed by vital customers. Scope and purpose In today's highly competitive marketplace, an increasing number of firms are being required to provide a high level of delivery performance by their customers. Certain types of vital customers, such as those operating under the JIT manufacturing philosophy, have very rigid delivery guidelines which must be adhered to on a consistent basis in order to retain their business in the long run. Prior studies that have considered this problem from a scheduling perspective have focused only on dispatching rules in machine constrained settings. However, in most real shops, dispatching rules are not the only means available in managing orders from vital customers. Instead, managers rely on flexible workers that can be moved to different departments as the shop load varies. The role of workers, and decision rules that govern worker assignment to different departments has not been considered in the context of managing vital customer priorities. The purpose of this study is to determine the relative importance of worker assignment and dispatching rules in offering a near-perfect delivery performance to vital customers served by the firm.