A clear understanding of sexual consent is important for sexual violence prevention. To date, most research has focused on how college students understand and negotiate consent. Although adolescence is a critical period for the development of sexual attitudes, identity, and intimate relationships, the perspectives of high school-aged youth have been largely absent from the consent literature. The current study investigated adolescents' attitudes toward affirmative consent in a sample of 226 high school students (58% female; 46% White, 24% Black, 25% Hispanic) from the southeastern U.S., as well as associations between affirmative consent attitudes and gender, gender role beliefs, and sexual activity status. Additionally, we tested whether gender role beliefs were a mediator between gender and affirmative consent attitudes. Overall, adolescents reported supportive attitudes toward affirmative consent. On average, girls and adolescents with more egalitarian gender role beliefs had more positive attitudes toward affirmative consent than boys and those with less egalitarian gender role beliefs, though no differences by sexual activity status were found. Gender role beliefs mediated the relationship between gender and attitudes toward affirmative consent. The results suggest that adolescents are generally supportive of affirmative consent practices, although some important group differences emerged.