Parents have the potential to protect against adolescent sexual risk, including early sexual behavior, inconsistent condom use, and outcomes such as pregnancy and sexually transmitted infections (STIs). Identification of the specific parenting dimensions associated with sexual risk in adolescence and young adulthood is necessary to inform and focus prevention efforts. The current study examined the relation of proximal (e.g., discussions of sexual costs) and distal (e.g., parental involvement, relationship quality) parenting variables with concurrent and longitudinal adolescent sexual behavior. The National Longitudinal Study of Adolescent Health (Add Health) provided a nationally representative sample with information about the family using adolescent and parent informants. Longitudinal information about sexual risk included adolescent condom use and adolescent sexual initiation, as well as young adult unintended pregnancy, reports of STIs, and biological assay results for three STIs. Higher parent-adolescent relationship quality was associated with lower levels of adolescent unprotected intercourse and intercourse initiation. Better relationship quality was also associated with lower levels of young adult STIs, even when accounting for prior sexual activity. Unexpectedly, more parent reports of communication regarding the risks associated with sexual activity were negatively associated with condom use and greater likelihood of sexual initiation. These results demonstrate that parents play an important role, both positive and negative, in sexual behavior, which extends to young adulthood, and underscores the value of family interventions in sexual risk prevention.