This study examined whether a comprehensive set of psychosocial factors was equally predictive of both adolescent vaginal intercourse and oral sex among 1,105 adolescents aged 12-16. Logistic regressions were used to examine the relationships between parental communication, religiosity, bonding to school, heavy drinking, sex expectancies, normative beliefs, and both oral sex and vaginal intercourse. Age, gender, bonding to school, heavy drinking, and negative health expectancies predicted both oral sex and vaginal intercourse. Parental communication was associated with vaginal intercourse but not oral sex. Behavior-specific normative beliefs were differentially associated with oral and vaginal sex.Few studies have examined the risk and protective factors associated with oral sex, despite recent findings suggesting that adolescents are more likely to engage in oral sex than vaginal intercourse (Prinstein, Meade, & Cohen, 2003;Remez, 2000). National data indicate that between 36% and 49% of adolescents aged 15-19 report having engaged in oral sex (Gates & Sonenstein, 2000; Hoff, Greene, & Davis, 2003). These data are cause for concern given research showing that oral sex places individuals at some risk for HIV and sexually transmitted infections (STIs) such as human papillomavirus (HPV) and gonorrhea (Edwards & Carne, 1998). Given the prevalence and potential risks associated with oral sex, it is important to understand the psychosocial factors that are predictive of involvement in this behavior in order to design effective prevention programs.A number of studies have found that psychosocial factors in the family, school, peer, and individual domains predict vaginal intercourse among adolescents (Kotchick, Shaffer, Forehand, & Miller, 2001;Resnick et al. 1997). Fewer studies have examined the relationship between these factors and oral sex. A recent study by Prinstein et al. (2003) indicates that adolescents who reported having had oral sex were more likely to report that their best friend had also had oral sex. In addition, a significant positive association was found between the friend's perceived number of oral sex partners and the total number of partners reported by the respondent. This was not the case when vaginal intercourse was examined, suggesting that adolescent oral sex behavior may be more susceptible to peer influences than vaginal intercourse. Adolescents who were rated as more popular by their peers were also more likely to have reported engaging in oral sex. However, among adolescents who had engaged in oral sex, those who reported a greater number of partners were less popular among their peers. These findings indicate a strong, yet complex relationship between peer sexual behavior and oral sex.The present study tests the implicit assumption underlying many sex education courses: psychosocial variables that predict adolescent vaginal intercourse extend to other risky sexual behaviors. The study will examine whether a comprehensive set of risk and protective factors is equally predictive o...