Suicide rates are rising among U.S. youth, yet our understanding of developmental mechanisms associated with increased suicide risk is limited. One high-risk pathway involves an interaction between heritable trait impulsivity and emotion dysregulation (ED). Together, these confer increased vulnerability to nonsuicidal self-injury (NSSI), suicide ideation (SI), and suicide attempts (SAs). Previous work, however, has been limited to homogeneous samples. We extend the Impulsivity x ED hypothesis to a more diverse sample of adolescents (N=344, ages 12-15 at Baseline, 107 males and 237 females) who were treated for major depression and assessed four times over two years. In multilevel models, the impulsivity x ED interaction was associated with higher levels and worse trajectories of NSSI, SI, and SAs. As expected, stressful life events were also associated with poorer trajectories for all outcomes, and NSSI was associated with future and concurrent SI and SAs. These findings extend one developmental pathway of risk for self-harm and suicidal behaviors to more diverse adolescents, with potential implications for prevention.