Background. Success after bariatric surgery requires behavioral modification. This study analyzes outcomes after Roux-en-Y gastric bypass surgery performed by a single surgeon between 1994 and 2002, and correlates preoperative factors with long-term outcome. Methods. A bariatric database has been maintained since 1994. Beginning in April 1997, patients completed preoperative and annual postoperative questionnaires that collected an array of psychosocial information. We hypothesized that certain attributes are predictive of success after surgery. Results. Of the 243 patients in our database, 181 enrolled after 1997. A total of 149 were seen for follow-up at 1 year. Life Experiences Survey (LES) scores and sexual satisfaction improved significantly. Perceived obesity-related health problems, motivation unrelated to social distress about obesity, a Sense of Coherence (SOC) score >110, and an LES score <-1 each independently predicted better weight loss (P < .05). A history of sexual abuse correlated with poorer weight loss (P < .05). Patients with more confidants, multiple previous dieting attempts, and greater anticipated postoperative diet-related stress tended toward better weight loss, but these data did not reach significance. Conclusions. Intrinsic motivational factors appear to predict greater weight loss after surgery. Ongoing follow-up will help determine the utility of preoperative evaluations and the role of preoperative intervention in those with poor predictive factors.