Objective: The purpose of this study was to investigate longitudinal trajectories of heavy drinking for males and females from adolescence to young adulthood, across the age span of 16-25 years, and to identify prospective predictors of the trajectory groups identified. Method: This study used semiparametric group-based mixture modeling to derive adolescent to young adult longitudinal trajectories of heavy drinking separately for 760 participants (430 females and 330 males) who have been participating in a long-term prospective study of risk factors for the development of heavy drinking and alcohol disorders. Results: Four trajectory groups were identified for males and five for females; the trajectories indicated both continuity and change in heavy drinking across time for the trajectory groups identified. Major common prospective predictors for the high and very high heavy drinking trajectory groups supported the influences of values and beliefs (e.g., religious commitment), stressful life events and substance use. Additional predictors for males included lower academic functioning and task orientation, and for females, more frequent sexual behavior and general deviance. Conclusions: In this predominantly white, middle-class sample, we identified groups of frequent, heavy drinking teens during the middle-adolescent years. Our findings suggest that the frequency of heavy drinking behavior will further increase for some teens into their young adult years. The potential adverse consequences of heavy drinking among adolescents and young adults suggests that multitargeted, gender-specific, early interventions with these high-risk teens is important.