Objective: Bariatric surgery is an effective treatment for obesity, which has been increasing worldwide. However, bariatric surgery causes dramatic physical changes that can cause significant stress. Prior research has found that psychological variables such as personality traits and levels of psychopathology can influence success after bariatric surgery (in terms of body mass index BMI reduction and weight loss). However, most prior studies have been limited by small sample sizes, inconsistent follow up, and categorical assessment of psychopathology. Method: The present study examines the predictive utility of the Personality Assessment Inventory (PAI) scales for three bariatric surgery outcomes (BMI reduction, weight loss, and percent excess weight loss %EWL) across 10 follow-up points 5 years after surgery. It also examines the largest sample of bariatric surgery-completing patients (N = 2,267) on the PAI to date. Latent growth modeling was used to examine change in the outcome variables. Results: Results indicate that personality and psychopathology variables predicted less BMI reduction, weight loss, and %EWL 5 years after surgery and also affected the trajectories of change in the outcome variables across time. The PAI scales predicted more variance in the 5-year BMI outcomes than did age and gender. The most robust effects were for scales assessing phobias, traumatic stress, identity problems, and negative relationships. Conclusion: The PAI may be useful to clinical health psychologists who conduct recommended psychological evaluations with potential bariatric surgery candidates.