A three-wave panel study with intervals of six months was conducted to examine the relationships between internalization of appearance ideals, body surveillance, valuing appearance over competence, and body consciousness during sexual activity among 238 Belgian adolescents who had engaged in sexual intercourse. Consistent with predictions, structural equation modeling indicated that greater internalization of appearance ideals at Wave 1 contributed to increased body surveillance and valuing appearance over competence at Wave 2. Body surveillance at Wave 2 and internalization at Wave 1 predicted higher body consciousness during sexual activity at Wave 3. Gender did not moderate these results, as model paths were similar in strength for girls and boys. These results further implicate the consequences of internalizing sociocultural practices that objectify boys and girls regarding adolescents’ initial sexual experiences.