Many of the most problematic behaviours characteristic of severely disturbed, aggressive, conduct-disordered children can be understood in terms of developmental arrests and distortions which have occurred on a crucial, early developmental line related to the mastery of separation anxiety and the integration of autonomy. A clinical investigation of psychoanalytic treatment of hyperaggressive children demonstrates the utility of this conceptualization for understanding the nature of their profound ego defects as psychologically treatable, developmental distortions in the realm of object relations, self-structure and ego development. This mode of understanding enables one to specify the point in development where ego distortion occurred, comprehend the nature of the psychopathology, plan effective treatment and evaluate therapeutic progress.