Methods: This is a prospective, randomized, controlled trial in patients with SMI who are obese and receiving treatment with medications that often have weight gain as a major side-effect. Participants are assigned to in-person MOVE! SMI, web-based MOVE! SMI with support from peer coaches, or a comparison group. Research assessments occur at 0, 3, 6, 9 and 12 months. Changes in outcomes are compared over time between the three groups. Comparative effectiveness is evaluated at 6 months. A secondary objective is to evaluate the extent to which gains are maintained at 9 and 12 months.