Multisystemic therapy (MST) is a family- and community-based treatment that has successfully served as a clinical and cost-effective alternative to out-of-home placements (e.g. incarceration, psychiatric hospitalisation) for youths presenting serious clinical problems. MST clinical procedures and findings from MST outcome studies are reviewed. Several key features differentiate MST from prevailing mental health and juvenile justice practices and probably account for its relative success. These features include interventions that comprehensively address the known determinants of clinical problems, the provision of services in home and community settings to promote service access and ecological validity, and a philosophy that emphasises provider accountability for family engagement and outcomes.