A model of alcohol use based on the theory of planned behavior, expectancy theory, and the developmental literature on the influence of parents and peers was examined with 87 eleventh grade students, 105 college freshmen, and 107 college juniors. Specifically, the influence of attitudes about the positive and negative consequences of drinking, perceived parental and peer norms about alcohol consumption, and perceived control over drinking predicted self-reported alcohol use. The results suggest that, during adolescence, decisions to consume alcohol are rational, based on the consideration of the positive consequences of alcohol use and perceptions of control over drinking; however, the negative consequences of alcohol use are discounted. While perceived peer norms predicted alcohol consumption in all three age groups, the influence of perceived parental norms varied such that they predicted alcohol use only among the college juniors. Implications and avenues for future research are discussed.