We examined a mediational model of the interrelationship of drug use, sexual risk, and impulsivity in a sample of young adults (N = 89), of which almost half displayed highly disruptive behaviors as children. We chose a mediational model given the emerging evidence that impulsivity is an underlying risk factor for many youth health risk problems, including sexual risk behaviors. The findings supported a partial mediational model in that the three target variables were significantly related to one another, yet the association of drug use and sexual risk was significantly reduced (although not to zero) when controlled by impulsivity. The findings support the view that the association of drug use and sexual risk behaviors is partially mediated by impulsivity, as well as the broader theory that youths with deficits in self-regulatory behavioral systems confer a greater likelihood of engaging in risky behaviors. Study implications and limitations are discussed. (Contains 4 tables.)