The aim of this Campbell Systematic Review was to evaluate the effect of multi‐systemic therapy (MST) on adolescents with social, emotional, and behavioural problems based on the best available evidence. The effect is measured by a range of behavioural and psychosocial outcomes, including the number of institutional placements and arrests, the incidence of drug abuse, and personal relationships, social skills, absence from school, etc.The review is exclusively based on randomised controlled trials in which random allocation between MST and usual treatment has taken place. 266 reports were selected on the basis of title and abstract. Of these 35 were found actually to be effect studies. And finally, eight of the 35 effect studies met the pre‐set quality criteria laid down in the original Campbell/Cochrane review.The Campbell/Cochrane review concludes that MST does not have consistently better effects than other types of interventions ‐ for example, restrictive institutional placement. On the other hand, nothing indicates that MST has any negative overall effects. All in all, MST does not seem to be any better or any poorer than other treatments. The Campbell/Cochrane review concludes that there are no consistent differences in outcome between the adolescents subject to MST and those subject to alternative treatment. This conclusion is based on the best available evidence on the effectiveness of MST.SynopsisResults of eight randomised controlled trials of Multisystemic Therapy (MST) conducted in the USA, Canada, and Norway indicate that it is premature to draw conclusions about the effectiveness of MST compared with other services. Results are inconsistent across studies that vary in quality and context. There is no information about the effects of MST compared with no treatment. There is no evidence that MST has harmful effects.AbstractBackgroundMultisystemic Therapy (MST) is an intensive, home‐based intervention for families of youth with social, emotional, and behavioral problems. Masters‐level therapists engage family members in identifying and changing individual, family, and environmental factors thought to contribute to problem behavior. Intervention may include efforts to improve communication, parenting skills, peer relations, school performance, and social networks. Most MST trials were conducted by program developers in the USA; results of one independent trial are available and others are in progress.ObjectivesTo provide unbiased estimates of the impacts of MST on restrictive out‐of‐home living arrangements, crime and delinquency, and other behavioral and psychosocial outcomes for youth and families.Search strategyElectronic searches were made of bibliographic databases (including the Cochrane Library, C2‐SPECTR, PsycINFO, Science Direct and Sociological Abstracts) as well as government and professional websites, from 1985 to January 2003. Reference lists of articles were examined, and experts were contacted.Selection criteriaStudies where youth (age 10–17) with social, emotional, and/or behavioral problems were randomised to licensed MST programs or other conditions (usual services or alternative treatments).Data collection & analysisTwo reviewers independently reviewed 266 titles and abstracts; 95 full‐text reports were retrieved, and 35 unique studies were identified. Two reviewers independently read all study reports for inclusion. Eight studies were eligible for inclusion. Two reviewers independently assessed study quality and extracted data from these studies.Significant heterogeneity among studies was identified (assessed using Chi‐square and I2), hence random effects models were used to pool data across studies. Odds ratios were used in analyses of dichotomous outcomes; standardised mean differences were used with continuous outcomes. Adjustments were made for small sample sizes (using Hedges g). Pooled estimates were weighted with inverse variance methods, and 95% confidence intervals were used.Main resultsThe most rigorous (intent‐to‐treat) analysis found no significant differences between MST and usual services in restrictive out‐of‐home placements and arrests or convictions. Pooled results that include studies with data of varying quality tend to favor MST, but these relative effects are not significantly different from zero. The study sample size is small and effects are not consistent across studies; hence, it is not clear whether MST has clinically significant advantages over other services.Reviewers' conclusionsThere is inconclusive evidence of the effectiveness of MST compared with other interventions for youth. There is no evidence that MST has harmful effects.