There is evidence of higher prevalence rates for alcohol use among rural adolescents relative to urban adolescents. Strategies aimed at preventing adolescent alcohol use typically include the development of social skills to resist peer pressure; among the social skills frequently targeted is assertiveness. Self-report data were collected from a sample of rural adolescents (N = 470) participating in a longitudinal preventive intervention study. Five hypothesized dimensions of assertiveness were validated with Confirmatory Factor Analysis: Specific Substance Refusal, Individual Rights, Transaction, Justice, and Social Approach. Using gender as a between-subjects factor, plus time and assertiveness as within-subjects factors to predict an alcohol use composite index, repeated measures analyses revealed a number of significant findings. Several assertiveness dimensions were found to have significant effects on the alcohol use index, and significant two-way and three-way interaction effects (gender x time x assertiveness dimension) also were found. Findings support the idea of including multidimensional assertiveness skill development as a component of preventive interventions, particularly for rural adolescents.