In the past decade, there has been renewed interest in the feasibility and efficacy of purely behavioral treatments for clinical depression. Emphasizing the functional aspects of depressive and nondepressive behavior, these treatments focus on the concept of behavioral activation, which guides implementation of procedures aimed at increasing patient activity and access to reinforcement. Although researchers have provided positive preliminary support for behavioral activation-based interventions, many fundamental issues concerning strategies, principles, and change processes involved in behavioral activation have yet to be addressed. In this paper, we compare and contrast contemporary behavioral activation interventions, explore strategies and process of change issues, clarify the basic behavioral principles underlying activation strategies, and outline questions that need to be addressed to improve outcomes and better understand the potential significance of behavioral activation as it pertains to the future of behavior therapy for depression.