© 2018 by the American Thoracic Society. Rationale: Physical inactivity among patients with chronic obstructive pulmonary disease is associated with exacerbations requiring high-cost health care utilization including urgent, emergent, and hospital care. Objectives: To examine the effectiveness of a behavioral lifestyle physical activity intervention combined with chronic obstructive pulmonary disease self-management education to prevent high-cost health care utilization. Methods: This was an analysis of secondary outcomes of the Chronic Obstructive Pulmonary Disease Self-Management Activation Research Trial, a two-arm randomized trial of stable adult outpatients with chronic obstructive pulmonary disease recruited from primary care and pulmonary clinics. Following a 6-week self-management education run-in period, participants were randomized to usual care or to a telephone-delivered homebased health coaching intervention over 20 weeks. Secondary outcomes of physical activity and health care utilization were determined by self-report 6, 12, and 18 months after randomization. Associations between treatment allocation arm and these secondary outcomes were examined using log-binomial and Poisson regression models. Results: A total of 325 outpatients with stable chronic obstructive pulmonary disease were enrolled in the trial. Their average age was 70.3 years (standard deviation, 9.5), and 50.5% were female; 156 were randomized to usual care and 149 to the intervention. A greater proportion of participants reported being persistently active over the 18-month follow-up period in the intervention group (73.6%) compared with the usual care group (57.8%) (mean difference, 15.8%; 95% confidence interval, 4.0-27.7%). This association varied by severity of forced expiratory volume in 1 second impairment(P for interaction = 0.09). Those in the intervention group with moderate impairment (forced expiratory volume in 1 second, 50-70% predicted), more frequently reported being persistently active compared with the usual care (86.0 vs. 65.1%; mean difference, 20.9%; 95% confidence interval, 5.7-36.1%). Patients with severe and very severe forced expiratory volume in 1 second impairment (forced expiratory volume in 1 second, 50% predicted) in the intervention group also reported being persistently active more frequently compared with usual care (63.3 vs. 50.8%; mean difference, 12.6%; 95% confidence interval,-4.7 to 29.8). The intervention was associated with a lower rate of lung-related utilization (adjusted rate ratio, 0.38; 95% confidence interval, 0.23-0.63) only among participants with severe spirometric impairment. Conclusions: Our results demonstrate that a feasible and generalizable home-based coaching intervention may decrease sedentary behavior and increase physical activity levels. In those with severe chronic obstructive pulmonary disease, this intervention may reduce lung disease-related health care utilization. Clinical trial registered with www.clinicaltrials.gov (NCT01108991).