Clinical researchers have recently begun to explore differences between psychotherapy outcome studies that focus on efficacy and those that focus on effectiveness. The authors provide concise descriptions of these research models, followed by more extended consideration of the most important conceptual and empirical distinctions between the two. Research on the efficacy/effectiveness distinction is then put into context: The common treatment variables that also influence treatment outcomes are reviewed. Fifty years of research on psychotherapy outcomes are next considered; contemporary research on the efficacy and effectiveness research models is emphasized. A description and evaluation of current efforts to heighten the value of technique-focused research to clinicians follow. The authors conclude by anticipating some promising future directions in this research domain.