The 35-year progression of multisystemic therapy (MST) from modest university-based efficacy studies to large-scale transport to community practice settings is described in this review. The success of early efficacy research led to effectiveness trials, and their success in decreasing rates of youth rearrest and incarceration led to multisite transportability trials and adaptations of the MST model for treating youth presenting other types of challenging clinical problems. To support the transport of MST programs to community settings, an intensive quality improvement system modeled after that used in clinical trials has been implemented in community-based MST programs for the past 15 years. With the association between therapist treatment fidelity and youth outcomes well established, transportability research has demonstrated the significant roles played by clinical supervisors, expert consultants, and provider organizations in supporting therapist adherence and youth outcomes. This body of work has been facilitated by federal and state initiatives to support evidence-based services.