The current study examined associations between posttraumatic stress disorder (PTSD) symptoms and future interpersonal victimization among adolescents, after accounting for the impact of early victimization exposure, gender, ethnicity, and household income. In addition, problematic alcohol use was tested as a mediator of the relation between PTSD symptoms and subsequent victimization. Participants included a national longitudinal sample of adolescents (N = 3,604) who were ages 12 to 17 at the initial assessment: 50% were male, and 67% were White, 16% African American, and 12% Hispanic. Cohort-sequential latent growth curve modeling was used to examine associations among the study variables. Baseline PTSD symptoms significantly predicted age-related increases in interpersonal victimization, even after accounting for the effects of earlier victimization experiences. In addition, alcohol problems emerged as a partial mediator of this relation, such that one fourth to one third of the effect of PTSD symptoms on future victimization was attributable to the impact of PTSD symptoms on alcohol problems (which, in turn, predicted additional victimization risk). Collectively, the full model accounted for more than half of the variance in age-related increases in interpersonal victimization among youth. Results indicate that PTSD symptoms serve as a risk factor for subsequent victimization among adolescents, over and above the risk conferred by prior victimization. This increased risk occurred both independently and through the impact of PTSD symptoms on problematic alcohol use. Based on these findings, it is hypothesized that the likelihood of repeated victimization among youth might be reduced through early detection and treatment of these clinical problems. (Contains 3 tables, 3 figures, and 4 footnotes.)