The most prevalent disordered eating pattern described in overweight youth is loss of control (LOC) eating, during which individuals experience an inability to control the amount of food they are consuming. LOC eating appears to be associated cross-sectionally with greater adiposity in children and adolescents, and appears to predispose youth to gain weight or body fat above that expected due to normal growth, thus likely contributing to obesity in susceptible individuals. Interpersonal Psychotherapy (IPT), a form of psychotherapy that has been adapted for the treatment of eating disorders, has demonstrated efficacy in reducing binge eating episodes and inducing modest weight loss (or at least weight stabilization) among adults diagnosed with binge eating disorder. We adapted group IPT for the targeted prevention of excessive weight gain (IPT-WG) among adolescent girls. Our pilot data support the feasibility and acceptability of a 12-week group IPT-WG trial among adolescent girls at high risk for obesity who report LOC eating, and preliminary findings suggest that IPT-WG has the potential to prevent excessive weight gain. We now propose an adequately powered clinical trial to evaluate the efficacy of IPT-WG compared to a standard-of-care health education for stabilizing weight and body fat gain trajectories in 117 adolescent girls at high risk for adult obesity who report LOC eating. Participants will be randomly assigned to a 12-week group IPT-WG or health education group; anthropometric variables will be measured at baseline, immediately after, and for up to 1 year following the initiation of treatment. We will assess the efficacy of IPT-WG in improving social functioning and reducing negative mood, disturbed eating patterns, and emotional distress. We also aim to determine the impact of IPT-WG on objective measures of LOC eating during a test meal and on appetitive hormones.