The purpose of this study was to explore the comparative contribution that (a) multiple sources of education about sexual topics (peers, media, school and other adults), and (b) the timing of this sex education, make on American adolescent sexual attitudes and behavior. Participants were 672 ethnically and economically diverse male and female, high-school adolescents. Regression analyses revealed that earlier learning from most sources and more learning from schools about various sexual topics, including the importance of using birth control and consequences of teen pregnancy, were generally significantly predictive of less frequent oral sex and sexual intercourse. Other sources of sex education (peers, media, other adults) seemed to be less important in influencing outcomes. Ethnic/racial and gender variations also resulted.