This report on sexual assault was written for adolescents. It contains data on teenage sexual assault from the National Youth Survey (NYS), a survey of a nationally representative sample of approximately 1,700 youths who were between 11 and 17 years old at the time of the project's initial interview and who were interviewed annually for 5 years (1976-1980). The data in this report came from the final 3 years of the NYS when detailed information about sexual assaults was obtained from all the self-identified victims and offenders. The research study is briefly described and then findings from the study are used to answer some of the most common questions teenagers ask about sexual assault: (1) what is sexual assault; (2) who is most likely to be sexually assaulted; (3) who is most likely to commit a sexual assault; (4) how often does sexual assault happen; (5) how many teenagers are sexually assaulted; (6) is there a typical sexual assault; (7) what causes a sexual assault; (8) what happens after a sexual assault; (9) what can teenagers do to prevent a sexual assault; and (10) what should you do if you are sexually assaulted. Advice for girls and for boys is given on how to prevent a sexual assault. (NB)