There is an ongoing debate if oppositional defiant disorder (ODD) and conduct disorder (CD) are valid and useful mental health disorders in children and adolescents, and how they relate to criminal and violent behaviors. Different subtypes of CD have been introduced in order to improve our understanding of the comorbidity, the course, the outcomes, and treatment needs of children and adolescents. This symposium gives an overview of the current epidemiological and clinical research on CD subtypes and its validity in general and forensic populations.