Preventing adolescent pregnancy is a national research priority that has had limited success. Programs have more successfully prevented teen pregnancy by supporting girls’ general adjustment than by directly targeting sexual behaviors and attitudes. The present study examined whether Multidimensional Treatment Foster Care (MTFC) relative to intervention services as usual (group care [GC]) decreased pregnancy rates among juvenile justice girls mandated to out-of-home care. Girls (ages 13-17) with histories of criminal referrals (Mdn = 10) were randomly assigned to MTFC (n = 81) or GC (n = 85) as part of two randomized controlled trials. Pregnancy histories were assessed from baseline through 24 months. Fewer postbaseline pregnancies were reported for MTFC girls (26.9%) than for GC girls (46.9%), an effect that remained significant after controlling for baseline criminal referrals, pregnancy history, and sexual activity. MTFC has previously been shown to decrease arrest and lock-up rates. These findings support the long-term preventive effects of MTFC on adolescent girls’ pregnancy rates.