Conduct disorder refers to a pattern of severe antisocial and aggressive behavior manifested in childhood or adolescence. This psychiatric diagnosis has been one of the most widely studied of all childhood disorders, and this extensive body of research has documented a large number of dispositional and contextual risk factors that can play a role in the etiology of this disorder. In this article, we provide a model for understanding these risk factors that use developmental theory to specify how these risk factors can negatively affect normative developmental mechanisms to place a child at risk for acting in an aggressive and antisocial manner, and recognize that there may be different mechanisms operating among individuals with this disorder. This approach for understanding the development of conduct disorder has important implications for diagnostic classification systems and for designing more effective interventions for youth with conduct disorder.