Conceptual and design essentials for evaluating mechanisms of change

Background: Considerable progress has been made toward the development of evidence-based treatments for a wide range of psychological disorders; however, little is known about the mechanisms through which these treatments actually lead to clinical change. Although the use of traditional randomized controlled treatment designs and tests of statistical mediation have significantly advanced understanding of psychological treatments, they are insufficient to test mechanisms of change. Method: This article outlines the conceptual and methodological requirements for evaluating mechanisms of change, highlights the importance of such a focus, and offers specific recommendations for research aimed at elucidating change mechanisms. Results and Conclusion: Conceptualizing and conducting studies that test mechanisms of change requires substantial modifications to traditional research designs, but doing so will significantly enhance scientific understanding as well as the efficiency and effectiveness of clinical interventions.