Drug prevention interventions frequently target early adolescents in order to stop or delay initiation of substance use. However, the prevalence and frequency of drug use escalate and then peak during emerging adulthood, making it important to determine whether drug use prevention efforts in adolescence have lasting effects into adulthood. Additionally, given differences in drug use frequency between ethnic groups, intervention effects by race should be examined when possible. This study evaluates the efficacy of a family-focused prevention program, Staying Connected with Your Teen®, delivered to parents and teens in the 8th grade, on family stressors during 9th and 10th grades, 10th-grade drug use (as potential mediators), and drug use frequency at age 20. Families (N = 331; Black = 163, White = 168) were randomly assigned to three conditions: parent-adolescent group-administered (PA), self-administered with telephone support (SA), and no-treatment control (Haggerty et al. Prevention Science, 8: 249-260, 2007). The impact of the intervention was assessed using latent variable structural equation models. Age 20 drug use frequency was significantly higher among Whites than Blacks as expected. The PA intervention had direct effects on reducing drug use frequency for both Blacks and Whites. The SA intervention had an impact on family stressors during adolescence for Whites, but not for Blacks. Results suggest that both formats for delivery were modestly efficacious for Whites, but only direct delivery was modestly efficacious for Blacks. Given the substantial savings in cost of the self-administered program over the group-administered format, improving the efficacy of self-administered programming for Blacks is recommended.