This study explored females' adolescent experiences with sexual aggression using event-level data. A community sample of women, ages 18 to 30 years (N = 319), were interviewed regarding their most recent unwanted sexual experience. Incidents were categorized as occurring during adolescence (ages 14 to 17) or adulthood (after age 18). Preliminary statistical comparison of adolescent and adult incidents revealed differences in perpetrators, type of aggression, preceding activities, and location of assault. Qualitative analytic techniques were then used to identify the contexts in which adolescent victimization occurred, as well as the factors contributing to adolescent vulnerability. Four contexts in which adolescents were sexually victimized emerged: Within Intimate Relationships, At Parties/Social Gatherings, Abuse by Authority Figures, and While Alone With a Friend. Thematic analysis revealed that inexperience with sex and dating, lack of guardianship, substance use, social and relationship concerns, and powerlessness contributed to adolescent vulnerability within these contexts.