In therapeutic foster care programs, youths who cannot live at home are placed in homes with foster parents who have been trained to provide a structured environment that supports their learning social and emotional skills. To assess the effectiveness of such programs in preventing violent behavior among participating youths, the Task Force on Community Preventive Services conducted a systematic review of the scientific literature regarding these programs. Reported and observed violence, including violent crime, were direct measures. Proxy measures were externalizing behavior (i.e., behavior in which psychological problems are acted out), conduct disorder, and arrests, convictions, or delinquency, as ascertained from official records, for acts that might have included violence. Reviewed studies assessed two similar interventions, distinguished by the ages and underlying problems of the target populations. Therapeutic foster care for reduction of violence by children with severe emotional disturbance (hereafter referred to as cluster therapeutic foster care) involved programs (average duration: 18 months) in which clusters of foster-parent families cooperated in the care of children (aged 5-13 years) with severe emotional disturbance. The Task Force found insufficient evidence to determine the effectiveness of this intervention in preventing violence. Therapeutic foster care for the reduction of violence by chronically delinquent adolescents (hereafter referred to as program-intensive therapeutic foster care) involved short-term programs (average duration: 6-7 months) in which program personnel collaborated closely and daily with foster families caring for adolescents (aged 12-18 years) with a history of chronic delinquency. On the basis of sufficient evidence of effectiveness, the Task Force recommends this intervention for prevention of violence among adolescents with a history of chronic delinquency. This report briefly describes how the reviews were conducted, provides additional information about the findings, and provides information that might help communities in applying the intervention locally.