A controlled trial comparing family therapy with individual supportive therapy in anorexia nervosa and bulimia nervosa was undertaken. Eighty patients (57 with anorexia nervosa; 23 with bulimia nervosa) were first admitted to a specialized unit to restore their weight to normal. Before discharge, they were randomly allocated to family therapy or the control treatment (individual supportive therapy). After one year of psychological treatment, they were reassessed, using body weight, menstrual function, and ratings on the Morgan and Russell scales. Family therapy was found to be more effective than individual therapy in patients whose illness was not chronic and had begun before the age of 19 years. A more tentative finding was the greater value of individual supportive therapy in older patients. To our knowledge, this is the first controlled trial of family therapy in anorexia nervosa and clarifies the specific indications for this treatment.