This analysis assessed patterns of sexual experience, the order in which behaviors were initiated, and associated factors, among Latino and African American ninth grade students (average age 15.2) who self-administered audio-computer-assisted surveys on netbooks in classes at 10 Los Angeles–area public high schools. Lifetime experiences with vaginal and oral sex were most common (19% and 16%, respectively); fewer reported anal sex (6%). Of the 23% reporting any sex, 91% fell into four categories- 36% reporting both oral and vaginal sex; 23% vaginal only; 18% all three; and 13% oral only. Most sexually experienced students (88%) initiated with vaginal or oral sex (46% vaginal, 33% oral, 9% both same day). No dominant pathway of sexual onset emerged for those reporting all three types of sex. We found no evidence that oral or anal sex substituted for or delayed vaginal sex. Males, those with a current partner, and those reporting multiple partners were more likely than others to report all three sexual behaviors versus vaginal only (odds ratios [ORs] 2.0, 1.5, 3.0; p = .02, .06, < .01, respectively). Although vaginal intercourse dominated their early sexual behavior, one-fifth of sexually experienced students reported anal intercourse, highlighting the need for specific prevention messages surrounding this higher-risk behavior.