The authors review the epidemiology, diagnosis and assessment, possible causes, and treatment of bulimia nervosa (BN). BN is the most common of the currently defined eating disorders, with a lifetime prevalence of 1%–3% in females in the general population. It is characterized by recurrent episodes of binge eating accompanied by a sense of loss of control over eating and by recurrent inappropriate compensatory behavior to avoid weight gain (e.g., vomiting, misuse of laxatives and diuretics, fasting, excessive exercise). A number of medical complications related to weight loss and to purging as well as increased rates of depression and anxiety disorders and alcohol and substance abuse often accompany BN. The assessment of BN should include a careful interview concerning the person's eating patterns and attitudes toward weight and food. The authors discuss possible causes of BN, include biological, psychological, family, and sociocultural theories. The most effective treatments for BN appear to be cognitive-behavioral psychotherapy and antidepressant medications. Some studies have found a combination of medication and psychotherapy more efficacious than either treatment used alone.