This chapter explores the phenomenon of renewal, a type of relapse triggered by a change in context (i.e., stimulus conditions) rather than reinforcement contingencies. Using controlled studies with nonhuman animals, the authors describe common renewal arrangements (ABA, ABC, and AAB) and their translational relevance to applied settings. Basic research has helped elucidate how context changes can lead to recurrence of extinguished behavior, highlighting the importance of programming for generalization and treatment robustness. The chapter offers a critical examination of Context Theory and suggests future research directions for improving understanding and mitigation of renewal. This foundational work informs clinical efforts to sustain treatment outcomes amid environmental changes.