The COPD Foundation operates a peer-led telephone-based information line, but its effectiveness in promoting adherence to O2 therapy and patient-centered outcomes is unknown. Our overall hypothesis is that a patient-centered Peer-Led O2 InfoLine for patients and CAregivers (PELICAN) will increase adherence and improve health. We have developed a broad-based collaboration with patients/caregivers, advocacy groups, a national O2 supplier, and others to conduct a 3-arm pragmatic clinical trial, to evaluate the comparative effectiveness of proactive vs. reactive PELICAN interventions vs. usual care on adherence to O2 (primary outcome) and on other patient-centered outcomes (secondary outcomes).