The firm's interest in monitoring and/or motivating workers appears to be an important reason why firms use pay supplements such as bonuses and overtime work. Using a representative sample of U.S. private industry jobs, this paper obtains some indirect evidence on what pay supplements serve as incentive instruments. I study how various pay supplements differ in both incidence and generosity when traditional incentive pay--pay based on individual results such as piece rates or sales commissions--is a part of job earnings. If a firm does use incentive pay the marginal benefit of a pay supplement as an incentive instrument should fall. Otherwise, the use of incentive pay should have no necessary relationship to provision of a pay supplement, with provision driven by worker preferences for the benefits provided.