Purpose:Little is known about factors associated with the day-to-day selection and orchestration of sexual repertoire among adolescent women. Analyzing differences in adolescent women's sexual activity may augment both the clinical and behavioral understanding of sexuality development and sexual decision making, and may yield important points to enhance existing programs for prevention of sexually transmitted infection or pregnancy. Methods: Adolescent women (N ϭ 387, aged 14 -17 years at enrollment) were recruited from primary care adolescent clinics serving primarily lower-and middle-income patients. Data were taken from daily sexual diaries. A four-category outcome variable, using generalized estimating equation multinomial logistic regression assessed the likelihood of specific sexual behaviors on a given day: none (abstinence), non-coital-only, coital-only, and dual noncoital/coitus. Separate models were analyzed for fellatio, cunnilingus, and anal sex. Predictor variables included age, menstrual bleeding, alcohol or marijuana use, positive or negative mood, recent coitus, recent noncoital sexual activity, partner support or negativity, sexual interest, feeling in love, time of the week, and same-day noncoital behaviors. Coital-only sexual behavior was used as the reference category. Results: Among adolescent women, abstinence is prevalent on the majority of days. When sexual activity does occur, coital-only activity is most common; however, noncoital behaviors alone and/or in tandem with coitus are not rare. Conclusions: Differing associations of intrapersonal, partner and situational variables with specific types of day-to-day sexual activity underscores a complex sexual repertoire which may be insufficiently examined with a simple focus on coital risk.Sexual activity among adolescent women is typically defined in terms of penile-vaginal sex, and is often depicted as sporadic and unplanned, primarily driven by external pressures and opportunity [1,2]. This perspective both ignores the complex combinations of genital and nongenital contact that may characterize a specific sexual encounter, as well as the ways in which these sexual encounters may be negotiated within the context of interpersonal, relational, cultural, and situational influences [3][4][5][6][7][8][9][10][11][12][13]. Approximately 50% of young women have ever participated in both penilevaginal intercourse and oral-genital sex, and about 25% have experienced a repertoire of penile-vaginal, oral, and anal sexual behaviors. However little is known about the phenomenology, or the day-to-day selection and orchestration of these behaviors within young women's lives. Such information may augment understanding of young women's sexual health [5,13,14] by providing a more detailed description of how aspects of sexuality are associated with event-level behaviors.Little is understood about the composition of the repertoire of sexual behaviors or the ways in which multiple