Little empirical research exists about highly effective psychotherapists, and none about the factors that mediate the acquisition and maintenance of superior performance skills (e.g., Ericsson, 1996, 2006; Ericsson, Krampe, & Tesch-Romer, 1993). In the full sample, a 3-level multilevel modeling (Level 1: clients; Level 2: therapists; Level 3: organization types) of practitioner outcomes was used to examine the contribution of the therapist to treatment effectiveness. Consistent with prior research, in the full sample (n = 69 therapists; n = 4,580 clients) it was found that therapist effects explained 5.1% of the variance in outcome, after adjusting for initial severity. Therapist gender, caseload, and age were not found to be significant predictors. In a subsample of therapists, the relationship between outcome and therapist demographic variables, professional development activities, and work practices was analyzed (n = 17 therapists, n = 1,632 clients). Therapist characteristics (e.g., years of experience, gender, age, profession, highest qualification, caseload, degree of theoretical integration) did not significantly predict client-reported outcomes. Consistent with the literature on expertise and expert performance, the amount of time spent targeted at improving therapeutic skills was a significant predictor of client outcomes. Further, highly effective therapists indicated requiring more effort in reviewing therapy recordings alone than did the rest of the cohort. Caveats and implications for clinical practice, continuing professional development, and training are discussed.

More than a dozen randomized controlled trials and several meta-analyses have provided strong empirical support for routine outcome monitoring (ROM) in clinical practice. Despite current enthusiasm, advances in implementation, and the growing belief among some proponents and policymakers that ROM represents a major revolution in the practice of psychotherapy, other research has suggested that the focus on measurement and monitoring is in danger of missing the point. Any clinical tool or technology is only as good as the therapist who uses it. Failing to attend to the therapist's contribution, the long neglected variable in psychotherapy outcome, ensures that efforts to create, research, and refine new outcome measurement systems will inevitably fall short. Research from the field of expertise and expert performance provides guidance for realizing the full potential of ROM.

In 1963, the first issue of the journal Psychotherapy appeared. Responding to findings reported in a previous publication by Eysenck (1952), Strupp wrote of the "staggering research problems" (p. 2) confronting the field and the necessity of conducting "properly planned an executed experimental studies" to resolve questions about the process and outcome of psychotherapy. Today, both the efficacy and effectiveness of psychotherapy has been well established. Despite the consistent findings substantiating the field's worth, a significant question remains the subject of debate: how does psychotherapy work? On this subject, debate continues to divide the profession. In this paper, a "way out" is proposed informed by research on the therapist's contribution to treatment outcome and findings from studies on the acquisition of expertise.

The monitoring of and continual promotion of the working alliance among military youth in the early phases of therapy may help therapists improve treatment outcomes.

Three methods for calculating effect sizes are recommended for moderating these differences, including two equations that show promise as valid and practical methods for use by clinicians in professional practice.