BACKGROUND: This study examines the temporal sequencing of sexting and sexual intercourse and the role of active sexting (sending a nude picture) in mediating the relationship between passive sexting (asking or being asked for a nude picture) and sexual behaviors. METHODS: Data are from Wave 2 (spring 2011) and Wave 3 (spring 2012) of an ongoing 6-year longitudinal study of high school students in southeast Texas. Participants included 964 ethnically diverse adolescents with a mean age of 16.09 years (56% female; 31% African American, 29% Caucasian, 28% Hispanic, 12% other). Retention rate for 1-year follow-up was 93%. Participants self-reported history of sexual activity (intercourse, risky sex) and sexting (sent, asked, been asked). Using path analysis, we examined whether teen sexting at baseline predicted sexual behavior at 1-year follow-up and whether active sexting mediated the relationship between passive sexting and sexual behavior. RESULTS: The odds of being sexually active at Wave 3 were 1.32 times larger for youth who sent a sext at Wave 2, relative to counterparts. However, sexting was not temporally associated with risky sexual behaviors. Consistent with our hypothesis, active sexting at Wave 2 mediated the relationship between asking or being asked for a sext and having sex over the next year. CONCLUSIONS: This study extends cross-sectional literature and supports the notion that sexting fits within the context of adolescent sexual development and may be a viable indicator of adolescent sexual activity.