New approaches to psychotherapy, which appear more effective than traditional ones in modifying several kinds of disturbed behavior, have recently been applied to the eating disorders. Patients with both anorexia nervosa and obesity have responded to behavior modification, and experience with obesity has already been sufficient to permit the development and description of relatively specific behavioral programs. These programs have been used to compare behavior modification in a systematic manner with a variety of alternate treatment methods. Every one of eight such studies has reported results favoring behavior modification, an unusual example of unanimity in this heterogeneous and complex disorder. Furthermore, some new experimental designs developed in these studies are making a significant contribution to the study of psychotherapy and the elucidation of its effective components.