Preventing adolescent pregnancy is a national research priority that has had limited success. In the present study, the authors 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 (13-17 years of age) with histories of criminal referrals (Mdn = 10) were randomly assigned to MTFC (n = 81) or GC (n = 85) as part of 2 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. The present findings support the long-term preventive effects of MTFC on adolescent girls' pregnancy rates. Findings are consistent with the notion that programs that target delinquency by impacting general risk behavior pathways and contexts may more successfully prevent teen pregnancy than those that directly target sexual behaviors. (Contains 2 tables, 1 figure, and 1 footnote.)