IMPORTANCE Clinical practice guidelines state there is insufficient evidence to support advising patients with peripheral artery disease (PAD) to participate in a home-based walking exercise program. OBJECTIVE To determine whether a home-based walking exercise program that uses a group-mediated cognitive behavioral intervention, incorporating both group support and self-regulatory skills, can improve functional performance compared with a health education control group in patients with PAD with and without intermittent claudication. DESIGN, SETTING, AND PATIENTS Randomized controlled clinical trial of 194 patients with PAD, including 72.2% without classic symptoms of intermittent claudication, performed in Chicago, Illinois between July 22, 2008, and December 14, 2012. INTERVENTIONS Participants were randomized to 1 of 2 parallel groups: a home-based group-mediated cognitive behavioral walking intervention or an attention control condition. MAIN OUTCOMES AND MEASURES The primary outcome was 6-month change in 6-minute walk performance. Secondary outcomes included 6-month change in treadmill walking, physical activity, the Walking Impairment Questionnaire (WIQ), and Physical and Mental Health Composite Scores from the 12-item Short-Form Health Survey. RESULTS Participants randomized to the intervention group significantly increased their 6-minute walk distance (reported in meters 357.4 to 399.8 vs 353.3 to 342.2 for those in the control group; mean difference, 53.5 95% CI, 33.2 to 73.8; P < .001), maximal treadmill walking time (intervention, 7.91 to 9.44 minutes vs control, 7.56 to 8.09; mean difference, 1.01 minutes 95% CI, 0.07 to 1.95; P = .04), accelerometer-measured physical activity over 7 days (intervention, 778.0 to 866.1 vs control, 671.6 to 645.0; mean difference, 114.7 activity units 95% CI, 12.82 to 216.5; P = .03), WIQ distance score (intervention, 35.3 to 47.4 vs control, 33.3 to 34.4; mean difference, 11.1 95% CI, 3.9 to 18.1; P = .003), and WIQ speed score (intervention, 36.1 to 47.7 vs control, 35.3-36.6; mean difference, 10.4 95% CI, 3.4 to 17.4; P = .004). CONCLUSION AND RELEVANCE A home-based walking exercise program significantly improved walking endurance, physical activity, and patient-perceived walking endurance and speed in PAD participants with and without classic claudication symptoms. These findings have implications for the large number of patients with PAD who are unable or unwilling to participate in supervised exercise programs. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00693940