Selecting the most appropriate treatment for each patient.

Reviews the emergence of research on fitting treatment procedures to the unique needs and proclivities of patients. Traditional research on efficacy of psychotherapy focuses on the role of interventions and theoretical brands, minimizing factors that cannot be randomly assigned. This line of research has not realized its initial and desired promise, perhaps because it fails to incorporate into the study of psychotherapy important and effective treatment variations that are associated with therapist and non-diagnostic patient factors. Contemporary efforts to "fit" treatments to patients emphasize the roles of interventions, participant factors, and contextual/relationship factors. For these complex interactions, any of which reflect factors that cannot be randomly assigned, randomized clinical trials (RCT) protocols are inappropriate as a "gold standard". Several studies are presented which illustrate not only the predictive power of incorporating both treatment mediators and moderators into the realm of psychotherapy study, but the value of a multi-method approach to research. Converging studies moreover, provide a way to incorporate matching algorithms into decisions about assigning optimal treatments.