This study examines factors associated with the implementation and short-term outcomes in dissemination sites of Multisystemic Therapy (MST), an intensive, short-term, family- and community-based treatment for serious antisocial behavior in youth. Participants were 666 children and families served by 217 therapists in 39 sites. Pre- (T1) to immediate posttreatment (T2) differences in child problems and functioning were similar in magnitude to those found in randomized trials of MST. Results of random effects regression supported direct effects of therapist adherence, organizational climate, and structure at baseline on immediate posttreatment child outcomes. However, organizational factors were unrelated to adherence; thus, a hypothesized mediation model in which organizational climate and structure affect outcomes through therapist adherence to MST was not supported. Furthermore, the direction of associations between some organizational climate variables and outcomes countered expectations. Post hoc moderation analyses clarify these findings, with organizational effects differing by level of therapist adherence during treatment. Implications for the transfer of evidence-based psychosocial treatments for youth to usual care practice settings are discussed.