Findings indicate that sexual debut was related to increases in adolescents’ self-concepts and risk-cognitions, both of which predicated risky sexual behavior. Early sexual onset was associated with an increase in sex prototype favorability, for all adolescents, and the increase in self-concept for the boys. The current analysis found evidence of reciprocal relations between prototypes and risk behaviors. Favorable prototypes predicted early sexual onset (onset within the next 2 years), which was associated with risky sexual behavior 3 years later. Positive effect of sexual onset of African-American adolescents’ self-concepts were revealed, as those who became sexually active showed a greater increase in self-concept than those adolescents who abstained. The effect was found despite the high stability of self-concept over time, and the effect was significantly stronger for boys than for girls. Furthermore, self-concept was related to later risky sexual behavior and consequences associated with risky sexual behavior. Thus it appears that some African-American adolescents view themselves more positively after the initiation of early sex. Post cross-sectional research has shown that self-esteem is positively related to sexual behavior for early adolescents, but is not related to sexual behavior among middle and late adolescence. Data did not suggest that low self-concept adolescents initiate sexual behavior to boost their self-concept. In fact, there was no relation between pre-debuted in self-concept and debut. The data suggest that adolescents with typical levels of self-concept experience an increase in self-concept after sexual onset. It is possible that other events or changes in adolescents’ lives that coincided with the timing of sexual onset may explain the observed increase in self-concept. The sample consisted of 733 African-American boys (328) and girls (405) from Iowa and Georgia. Tables, figure, note, references