Two-Year Follow-up of a Randomized Effectiveness Trial Evaluating MST for Juveniles Who Sexually Offend LetourneauElizabeth J. HenggelerScott W. McCartMichael R. BorduinCharles M. SchewePaul A. ArmstrongKevin S. 2014 Objective: Building on prior efficacy trials (i.e., university based, graduate students as therapists), the primary purpose of this study was to determine whether favorable 12-month outcomes obtained in a randomized effectiveness trial (i.e., implemented by practitioners in a community mental health center) of multisystemic therapy (MST) with juveniles who had sexually offended (JSO) were sustained through a second year of follow-up. Method: JSO (n = 124 male youth) and their families were randomly assigned to MST, which was family based and delivered by community-based practitioners, or to treatment as usual (TAU), which was primarily group-based cognitive-behavioral interventions delivered by professionals within the juvenile justice system. Youth averaged 14.7 (SD = 1.7) years of age at referral, were primarily African American (54%), and 30% were Hispanic. All youth had been diverted or adjudicated for a sexual offense. Analyses examined whether MST effects reported previously at 1-year follow-up for problem sexual behaviors, delinquency, substance use, and out-of-home placement were sustained through a second year of follow-up. In addition, arrest records were examined from baseline through 2-year follow-up. Results: During the second year of follow-up, MST treatment effects were sustained for three of four measures of youth problem sexual behavior, self-reported delinquency, and out-of-home placements. The base rate for sexual offense rearrests was too low to conduct statistical analyses, and a between-groups difference did not emerge for other criminal arrests. Conclusions: For the most part, the 2-year follow-up findings from this effectiveness study are consistent with favorable MST long-term results with JSO in efficacy research. In contrast with many MST trials, however, decreases in rearrests were not observed.