This chapter highlights the importance of promoting persistence of socially desirable behavior to ensure long-term maintenance of treatment effects. Desirable behaviors, such as communication or task engagement, must withstand treatment disruptions to prevent relapse. Empirical studies are reviewed to demonstrate how reinforcement rate, magnitude, and delay impact persistence. While much research has focused on relapse of challenging behavior, this chapter underscores the need to also strengthen desired behavior. Applied implications and recommendations for promoting durable behavior change are discussed.