Evaluated the outcomes of 130 indicated preventive interventions (secondary prevention) mental health programs for children and adolescents that seek to identify early signs of maladjustment and to intervene before full-blown disorders develop. Results indicate such programs significantly reduce problems and significantly increase competencies. In particular, behavioral and cognitive-behavior programs for children with subclinical disorders (mean ESs in the 0.50s) appear as effective as psychotherapy for children with established problems and more effective than attempts to prevent adolescent smoking alcohol use, and delinquency. In practical terms, the average participant receiving behavioral or cognitive-behavior intervention surpasses the performance of approximately 70% of those in a control group. Of particular interest was the high mean effect (0.72) achieved by programs targeting incipient externalizing problems which are customarily the least amenable to change via traditional psychotherapeutic efforts when they reach clinical levels. Priorities for future research include greater specification of intervention procedures, assessment of treatment implementation, more follow-up studies, and identifying how different participants respond to early intervention.