Teen pregnancy is associated with a host of deleterious outcomes for girls such as drug use and poor parenting. Thus, reducing teen pregnancy rates could improve long-term developmental outcomes for girls, improving adjustment during young adulthood. Based on the positive effects of Multidimensional Treatment Foster Care (MTFC) relative to group care (GC) in a study of adolescent girls—significantly fewer pregnancies reported in the 2-year follow-up for MTFC girls—the present study followed this sample into young adulthood (approximately 7 years postbaseline) to examine the effects of adolescent pregnancy on young adult substance use and pregnancy-related outcomes. All participants were randomly assigned to MTFC (n = 81) or GC (n = 85) as adolescents as part of two RCTs. Results from logistic regression analyses indicated that becoming pregnant during the 2-year follow-up was significantly related to illicit drug use, miscarriage from a new pregnancy, and child welfare involvement at 7 years postbaseline. In addition, baseline marijuana use predicted marijuana use at 7 years postbaseline.