Study 2 - Treatment study: A cohort of approximately 100 women with obesity (BMI > 30) and no current depressive disorder will be enrolled in a 6-month state-of-the-art group weight loss treatment. Approximately 200 women with comorbid obesity and depression will be randomly assigned to either the identical weight loss treatment or to a combined cognitive-behavior group therapy program focused on both depression and weight loss. Aims of the treatment study will include: