PURPOSE:Determine if a "nondieting" intervention focused on intensive training in eliciting the relaxation response enhances health outcomes compared with nondieting interventions without such training. DESIGN:Randomized trial with follow-up at 10 weeks, 4 months, and 12 months. SETTING:General community. SUBJECTS:Total of 225 overweight and obese women with at least one other cardiovascular risk factor. INTERVENTIONS:Three 10-week nondieting interventions: a group program (P1) focused on intensive training in techniques for eliciting the relaxation response (n = 60), a group program (P2) focused on healthy eating and physical activity (n = 61), and a self-guided, mail-delivered version of P2 (P3; n = 101). MEASURES:The Revised Symptom Checklist measured psychological distress, the Medical Symptoms Checklist measured the experience of medical symptoms, and the Health-Promoting Lifestyle Profile measured a range of lifestyle behaviors. Self-efficacy for low-fat eating intuitive eating, and body mass index were also assessed. ANALYSIS:An intention-to-treat analysis was used. RESULTS:At 12 months, P1 produced statistically greater improvements in stress management behaviors and medical symptom discomfort and was the only program to significantly improve self-efficacy for low-fat eating. In P1, the effect sizes for reductions in depression (0.75) and interpersonal sensitivity (0.85) were large. At 12 months, mean weight was unchanged. CONCLUSION:Inclusion of intensive relaxation response training in a nondieting program for overweight women enhanced stress management and medical symptoms outcomes but not weight outcomes.