Freud's psychodynamic theory is predominantly based on case histories of patients who displayed abnormal behavior. From a scientific point of view, Freud's analyses of these cases are unacceptable because the key concepts of his theory cannot be tested empirically. However, in one respect, Freud was totally right: most forms of abnormal behavior originate in childhood. In this paper various factors are discussed that play a role in the etiology of abnormal behavior in children and adolescents. Furthermore, problems are signaled that hinder effective interventions for disordered youths.