Using the National Longitudinal Study of Adolescent Health, we tested latent growth models examining whether the number of friends using alcohol and family cohesion was linked with trajectories of binge drinking (N = 3,342) from adolescence (average age 15.06) into young adulthood (average age 27.93). Adolescents with higher family cohesion had lower rates of binge drinking in adolescence (b = −.07, p < .05), while those with more friends drinking alcohol were more likely to binge drink in adolescence (b = .51, p < .001), young adulthood (b = .22, p < .001), and had increasing trajectories of binge drinking across 14 years (b = −.29, p < .001). Clinically, we discuss Multiple‐Family Group Interventions as a potential approach.