PROJECT SUMMARY/ABSTRACT The proposed study is designed to evaluate the efficacy of a remotely-delivered, acceptance-based behavioral intervention (ABTi) for individuals demonstrating weight regain after bariatric surgery by comparing it to a Control condition. The current study aims to: 1) evaluate ABTi's efficacy on weight outcomes compared to Control; 2) evaluate ABTi's efficacy on secondary outcomes including improvements in eating behaviors, physical activity, and medical conditions compared to Control; 3) test proposed mechanisms of action, including evaluating a) if changes in hypothesized active ingredients in ABTi mediate differences in weight outcomes between conditions and b) if the association between eating behavior and subjective internal states (i.e., hunger, cravings, urges, negative affect) will weaken in ABTi compared to Control. Patients 6 to 48 months out from surgery who have regained >5% of their weight will be randomized to ABTi or Control (n=200). Assessments willbe conducted at baseline, 3, 6 (end of active treatment), and 12 months (follow up) after enrollment. Developing innovative interventions to reverse postoperative weight regain is crucial to maintain the health benefits of surgery in this growing population of patients not experiencing optimal postoperative results.