Risky driving behaviors are disproportionately high among young adults and impulsivity is a robust risk factor. Recent conceptualizations have proposed multidimensional facets of impulsivity comprised of negative urgency, premeditation, perseverance, sensation seeking, and positive urgency (UPPS-P model). Prior studies have found these facets are associated with risky driving behaviors in college student samples, but no prior studies have examined these facets in clinical samples. This study examined the unique and interactive effects of UPPS-P impulsivity facets on past-year risky driving behaviors in a sample of high-risk young adults (ages 18-30 years) with a history of substance use and antisocial behavior and their siblings (n=1,100). Multilevel Poisson regressions indicated that sensation seeking and negative urgency were uniquely and positively associated with both frequency of past-year reckless driving and driving under the influence. Moreover, lack of premeditation was uniquely and positively associated with reckless driving, whereas lack of perseverance was uniquely and positively associated with driving under the influence. Furthermore, lack of premeditation moderated and strengthened the positive association between sensation seeking and driving under the influence. These study findings suggest that assessing multiple facets of trait impulsivity could facilitate targeted prevention efforts among young adults with a history of externalizing psychopathology.