OBJECTIVE: To examine binge eating, depression, weight self-efficacy, and weight control success among obese individuals seeking treatment in a managed care organization. DESIGN: Gender-stratified analyses of associations between binge eating, depression, weight self-efficacy, and weight change, using data from a randomized clinical trial that compared low-cost telephone-based, mail-based, and usual care interventions for weight loss. SUBJECTS: A total of 1632 overweight individuals (460 men, 1172 women; mean age: 50.7 y; mean body mass index: 34.2 kg/ m2) were recruited from a large Midwestern US managed care organization. MEASUREMENTS: Height and weight were measured by study personnel at baseline, and self-reported weight was assessed at 6 and 12 months; self-reported depression status, binge eating, and self-efficacy for weight control were assessed at baseline. RESULTS: Lifetime prevalence rates for depression and probable binge eating disorder were high. Weight self-efficacy was inversely related to weight in both men and women. For women, depression was associated with lower weight self-efficacy and higher body weight. Women reporting depression or lower weight self-efficacy at baseline had less weight loss success at 6 and 12 months. Depression, binge eating disorder, and weight self-efficacy were not significantly associated with weight loss success in men. CONCLUSION: Negative emotional states are highly prevalent and predict poor treatment outcomes, particularly for obese women. As obese women with clinical depression typically are excluded from intervention studies, further research on how to address the intersection of obesity intervention and mood management may be warranted.