Identification of patient characteristics that are associated with behavioral weight loss success among bariatric surgery candidates could inform selection of optimal bariatric surgery candidates. We examined the associations between psychosocial characteristics and weight loss in a group of Veterans with severe obesity who participated in a behavioral weight loss intervention. The MAINTAIN trial involved a 16-week weight loss program followed by randomization among participants losing at least 4kg to a maintenance intervention or usual care. This secondary analysis was performed on Veterans who participated in the 16-week weight loss program and met NIH criteria for bariatric surgery (body mass index [BMI] 35.0-39.9 with at least 1 obesity-related comorbidity or BMI≥40). Unadjusted and adjusted associations between baseline patient characteristics and weight loss during the 16-week induction phase were evaluated with linear regression. Missing weight measurements were multiply imputed, and results combined across ten imputations. Among the 206 patients who met inclusion criteria, mean initial BMI was 40.8kg/m2 (SD 6.0), and mean age was 59.2years (SD 9.4). Approximately 20% of participants were female, 51.5% were Black, and 44.7% were White. Estimated mean 16-week weight loss was 5.16kg (SD 4.31). In adjusted analyses, greater social support and older age were associated with greater weight loss (p<0.05). None of the nine psychosocial characteristics we examined were associated with greater weight loss. Understanding and strengthening the level of social support for bariatric surgery candidates may be important given that it appears to be strongly correlated with behavioral weight loss success. Level II, Evidence obtained from well-designed controlled trials without randomization. ClinicalTrials.gov NCT01357551 http://clinicaltrials.gov/show/NCT01357551 .