Because of continuing diagnostic confusion, little empirical evidence exists to guide the clinician in treating patients with antisocial and borderline personalities. However, there is an extensive clinical literature based on the experience of many workers in the field, and it is possible to outline broad areas of agreement and major controversies. The resistance of the patient and the intense counter transference he typically evokes make treatment difficult no matter what the approach. Most authors agree that treatment of the antisocial personality must begin in a residential setting with an active milieu if it is to have any chance of success. Severe borderlines may also require a great deal of structure to supplement psychotherapy; with them, however, the therapist canfeel more optimistic about an approach stressing the clarification of maladaptive defenses and the interpretation of negative transference.