The expression of human sexuality during the dating relationships of adolescents is exceedingly commonplace. Previous research has hinted that partner characteristics may influence the sexual behaviors and attitudes of adolescents. The current study fills a gap in the literature by examining whether boyfriends’ age influences the sexual behaviors and attitudes of adolescent girls. Two main hypotheses were tested: (1) that girls with older boyfriends would engage in more advanced sexual behavior and all forms of sexual intercourse; and (2) that girls with older boyfriends would engage in more unsafe sexual behavior. Participants were an ethnically diverse group of 146 girls in the 9th grade from San Francisco Bay Area high schools who had been or were currently in a serious romantic relationship. Participants completed a questionnaire that included measures for five dimensions of sexual attitudes, two classes of sexual motives, seven normative sexual behaviors, and three types of risky sexual practices. Results of correlation, chi-square, and MANOVA and ANOVA analyses revealed that girls with older boyfriends were more likely to engage in all forms of sexual intimacy, to have sex under the influence of alcohol or drugs, and to experience sexual coercion than were girls with similar-aged boyfriends. Moreover, in comparison to girls with similar-aged boyfriends, girls with older boyfriends were more likely to agree that men are sexually driven, that sex is spontaneous, and that sex represents maturity. Given these findings, especially findings that indicate that sexual intimacy between girls and older boyfriends may occur under unsafe conditions, further investigation is warranted. Parents, counselors, and sex education teachers should be aware of the special risks associated with adolescent females dating older males. Tables, appendix, references