Bridging the gap between lab and clinic has become a rallying cry for a generation of treatment researchers, and identifying and overcoming barriers to successful dissemination of best-practice treatment has become a major public mental health priority. In this review, the authors argue that a key limit to accomplishing this goal may be found back in the original research laboratories where these treatments were developed. Despite 50 years of research and 1,500 clinical trials, there are surprisingly little data on what makes youth psychotherapy therapeutic. To illustrate the problem this poses for dissemination, the adolescent depression literature is reviewed in terms of (a) critical core components of intervention and (b) basic processes through which these techniques operate. Process-outcome relationships in cognitive-behavioral, interpersonal, and family therapy models are examined with descriptive meta-analytic techniques. Discussion of treatment dissemination follows, focusing on the value of basic research on core psychotherapeutic techniques and processes.