In this study, the authors examined the long-term criminal activity of 176 youths who had participated in either multisystemic therapy (MST) or individual therapy (IT) in a randomized clinical trial (C. M. Borduin et al., 1995). Arrest and incarceration data were obtained on average 13.7 (range = 10.2-15.9) years later when participants were on average 28.8 years old. Results show that MST participants had significantly lower recidivism rates at follow-up than did their counterparts who participated in IT (50% vs. 81%, respectively). Moreover, MST participants had 54% fewer arrests and 57% fewer days of confinement in adult detention facilities. This investigation represents the longest follow-up to date of a MST clinical trial and suggests that MST is relatively effective in reducing criminal activity among serious and violent juvenile offenders.