Approximately two-thirds of all adults and close to 75% of Veterans are overweight or obese, making obesity a national epidemic with significant impairments in physical and psychological functioning, increasing healthcare costs, and high mortality rates. A significant proportion of overweight and obese individuals binge eat in response to stress or negative emotions, further contributing to obesity. Obesity and binge eating are independently related to a number of physical and mental health co-morbidities such as diabetes, coronary heart disease, osteoarthritis, respiratory symptoms, depression, and anxiety. Although behavioral weight loss interventions have been partially effective, few show long-term maintenance of weight loss, especially for patients with binge eating behavior. Thus, a stepped-care approach that provides more intensive treatment to specifically address the emotional and behavioral factors associated with problematic eating and obesity may be necessary. Acceptance and Commitment Therapy (ACT), an empirically-supported intervention that is being rolled out nationally by the VA, has been effective in reducing distress, increasing quality of life, and improving other indices of health in a wide range of conditions from depression to diabetes. The investigator's preliminary findings suggest that a brief ACT-based group intervention for patients with overweight or obesity can substantially reduce binge eating and distress, and improve functioning. This study proposes to test the efficacy of an ACT intervention for binge eating in conjunction with a standard behavioral weight loss intervention, Managing Overweight and/or Obesity for Veterans Everywhere (MOVE!), at the VA San Diego Healthcare System (VASDHS). Patients (N = 154) who are overweight or obese (body mass index \> 25 kg/m2) and meet the clinical criteria for binge eating will be randomized to receive either four 2-hour weekly ACT intervention groups or brief MOVE-II active control groups after their participation in MOVE!. This study hypothesizes that: 1) patients in the ACT intervention will experience significantly greater reductions in binge eating severity than patients in the brief MOVE-II active control group (primary outcome); 2) patients in the ACT intervention will experience significantly greater improvements in physical and mental health functioning, obesity-related quality of life, physical activity levels, caloric and nutrient intake, emotional distress symptoms, binge frequency, and other forms of emotional eating than patients in the brief MOVE-II active control group; 3) gains associated with the ACT intervention will be maintained longer than gains associated with the brief MOVE-II active control group; 4) at 3-month and 6-month follow-ups, patients in the ACT intervention will have greater decreases in body mass index compared to patients in the brief MOVE-II active control group; and 5) measures of acceptance and action will mediate treatment response in the ACT intervention on outcomes of interest. Given the significant physical and psychological sequelae of binge eating and obesity, a brief intervention that can reduce disordered eating, enhance the maintenance of weight loss, and improve functioning among patients who suffer from binge eating, could be critical in the comprehensive approach to patient care at the VA.