Progression of ACT

Abstract Acceptance and commitment therapy (ACT) in the context of its historical and progressive development unfolded within three phases over the past 40 years. Events and influences in an initial phase that culminated in the development of comprehensive distancing as a precursor to ACT in the early 1980s preceded philosophical, theoretical, and conceptual refinements that took place during the next phase of ACT’s progression. These advancements, including the further explication of functional contextualism, rule governance, and relational responding, contributed to the emergence of ACT as a coherent transdiagnostic intervention by the turn of this century. Ever increasing outcome and process research within the last two decades during ACT’s third and most recent stage of progression have been instrumental in solidifying its current empirical status and expanding globalization.