Bariatric surgery has been recommended as a treatment for patients with clinically severe obesity (National Institutes of Health Consensus Development Panel, 1992). Although surgery leads to significant, long-term weight loss for a majority of patients, 20% of patients fail to lose a significant amount of weight or experience significant weight regain (Benotti & Forse, 1995). Currently, there is little evidence to suggest who will or will not achieve satisfactory weight loss after bariatric surgery. In this article, we provide background information on the procedures of gastric bypass and gastroplasty, the associated risks and complications, and outcomes. We review studies on the relationship of psychological variables to weight loss after operation, including recent findings that binge eating may be associated with poorer long-term outcomes. We outline several important roles the cognitive behavior therapist can play in treating individuals in the preoperative, postoperative, and longer-term adjustment phases. The cognitive behavior therapist can make a significant contribution to the management of the bariatric surgery patient and in the development and evaluation of interventions to enhance compliance and maximize weight loss, psychosocial functioning, and health-related quality of life after surgery.