Resurgence refers to a relapse that occurs following worsening conditions of alternative reinforcement, and it poses a threat to the long-term maintenance of treatment effects produced by differential-reinforcement based interventions. “Resurgence as Choice,” or RaC, is a quantitative theory that may help researchers and clinicians identify variables that affect resurgence. RaC suggests that resurgence is governed by the same basic processes that are thought to govern choice, and this simple way of thinking about resurgence is the most recent and general quantitative theory of resurgence to date. In this chapter, we describe the resurgence research on which RaC is based. We then describe RaC, placing emphasis on its broad arguments, the quantitative framework that formalizes those arguments, and recent modifications to RaC’s core models that allow the theory to describe a broad swath of outcomes from the research on resurgence and resistance to change. We close by emphasizing the clinical utility of RaC for those interested in using the quantitative analysis of behavior to produce more durable behavior change.