Study Objective and Design: Unintended pregnancy rates in the United States remain high among adolescents. Emergency contraception (EC) provides the only option for pregnancy prevention after unprotected sex. To better define the population of adolescents who request and use EC pills, we performed a post hoc analysis of an over-the-counter simulation study of EC pills. Setting: Teen reproductive health clinics in 5 cities. Participants: Adolescents between the ages of 13 and 17 years who requested EC. Interventions: Single-tablet levonorgestrel 1.5 mg. Main Outcome Measures: We calculated the correlations between age and baseline sexual and contraceptive behaviors. x(2) Tests were used to compare behaviors of first-time and repeat EC users. Results: Overall, the most commonly reported contraceptive methods ever used were condoms, oral contraceptives, none, and withdrawal; the most common method ever used in each age group was no method for 13- to 14-year-olds and condom for 15-, 16-, and 17-year-olds. The percentage of participants who had never used contraception before requesting EC decreased with age (53% [20/28] of 13- to 14-yearolds vs 15% [10/65] of 17-year-olds). First-time EC users were more likely to report no previous contraceptive use compared with repeat EC users (42% [88/208] vs 10% [13/135]; P <.001). Regardless of age, the most commonly reported reason for requesting EC was nonuse of any contraceptive method (ie, "unprotected sex"). Conclusion: Adolescents who requested EC most commonly reported ever-use of contraceptive methods that rely on user adherence or no method at all, with younger adolescents more likely than older adolescents to have used no previous method. The provision of EC presents an opportunity to provide education and access to highly effective, long-term contraceptive methods.