Children with attention deficit/hyperactivity disorder (ADHD) are at heightened risk for maltreatment and later substance use disorders (SUDs). We investigated the relationship of childhood maltreatment and other risk factors to SUDs among adolescents diagnosed with ADHD in childhood. Eighty adolescents diagnosed with ADHD when they were 7 to 11 years old were screened for histories of childhood maltreatment, and SUD diagnoses were formulated in accordance with the 4th edition of the "Diagnostic and Statistical Manual of Mental Disorders." Lifetime history of problematic substance use was obtained for each parent at baseline. Childhood maltreatment predicted SUD outcome over and above that accounted for by childhood conduct disorder and problematic parental substance use, two potent predictors of adolescent SUDs. (Contains 3 tables.)