This study explored the relations between Latino gender role attitudes (traditional machismo attitudes and caballerismo attitudes) and sexual behaviors among 242 Mexican American early adolescent boys in the southwest United States. Specifically, a multiple mediator model estimated the association between gender role attitudes and sexual activity through a mediational pathway connecting substance use, sexual motives, and peer influence. Results from analyzing this structural equation model indicated that traditional machismo attitudes were not associated with sexual behaviors. Caballerismo gender role attitudes, however, were indirectly linked with reduced sexual motives and substance via peer influence. This study underscores the importance of social context, behavior, and psychological motivations in explaining differences in sexual motives and substance use among young Mexican American adolescent boys who hold different kinds of beliefs about their gender.