Background: This study examined conduct disorder (CD) and major depression (MDD) in adolescents in relationship to parent-child conflict and psychopathology in their parents. Method: Participants were drawn from a population-based sample of twins and their families. Affected participants had lifetime diagnoses of CD and/or MDD; controls had no history of either disorder. Results: The presence of CD or MDD in an adolescent was related to increased rates of maternal MDD and paternal antisocial behavior. Both CD and MDD in adolescents were directly associated with high parent-child conflict. This association appeared unrelated to whether the father had a history of antisocial behavior; however, the association between mother-child conflict and psychopathology in the child was related to the mother having a history of MDD as well. Conclusion: The implications of these findings for the complex relationship between parental diagnoses, child diagnoses, and parent-child conflict are discussed.