There is a growing consensus that bariatric surgery is the treatment of choice for extremely obese individuals who have failed to reduce their weight satisfactorily using behavioral or pharmacologic interventions. The gastric bypass in particular is associated with excellent long-term weight loss. Although most extremely obese individuals will have essentially normal psychological functioning, a significant minority suffer from depression, binge eating, trauma, or other emotional complications that may require treatment before or after bariatric surgery. A structured behavioral assessment, conducted by a mental-health professional and a registered dietitian, can readily identify those who are most likely to require adjunct counseling.