Telephone interviews were conducted in 1992 with a nationally representative sample of 2,000 youths aged 10-16 and their caretakers. More comprehensive school programs had mixed, small, but overall positive effects. Children exposed to such school-based prevention programs performed better on a short test of knowledge about sexual victimization; when victimized or threatened, they were more likely to use the self-protection strategies recommended by prevention educators. They were also more likely to feel that they had been successful in protecting themselves and were more likely to disclose to someone the victimization attempts. They were not better able to limit the seriousness of the assaults and, in fact, they experienced more injuries in the course of sexual assaults. Comprehensive parental instruction also had positive effects on knowledge, the use of preferred self-protection strategies, and the likelihood of disclosure. Children with comprehensive parental instruction were more likely to limit the seriousness of assaults. 6 tables and 19 references