Chronic obstructive pulmonary disease (COPD) is a progressive lung disease that is highly prevalent among veterans. Pulmonary rehabilitation which incorporates exercise training and self-management education is recommended as standard management for COPD and aims to increase daily activity and quality of life through improvement in symptoms and exercise tolerance and prompting health behavior change. Although insomnia is common is veterans with COPD, the self-management education component of pulmonary rehabilitation does not address sleep, thus potentially explaining the lack of improvement in sleep following pulmonary rehabilitation. Insomnia can substantially impact the intended treatment goals of pulmonary rehabilitation as it has been found to be associated with limitations in activities of daily living (ADL), lower levels of physical activity, poor quality of life, greater COPD symptoms, and reduced exercise performance. Given that sleep is not addressed as part of pulmonary rehabilitation, untreated insomnia may partly account for the declines in quality of life and exercise capacity and absence of increased daily activity often reported following pulmonary rehabilitation. Implementing an insomnia-specific treatment in COPD patients undergoing pulmonary rehabilitation is likely to lead to improvements in sleep that could facilitate maintenance of gains in quality of life and exercise capacity and enhance daily activity levels following pulmonary rehabilitation. Cognitive- behavioral therapy for insomnia (CBT-I) not only improves sleep-specific symptoms of insomnia but also improves quality of life, reduces ADL limitations, and improves condition-specific symptoms. We postulate that CBT-I as an adjunct to home-based pulmonary rehabilitation for COPD patients with insomnia will lead to improvement in sleep quality that will facilitate achievement of optimal and enduring functional outcomes following pulmonary rehabilitation. To test this hypothesis, we will conduct a randomized controlled trial of veterans with COPD and insomnia enrolled in home-based pulmonary rehabilitation assessed pre-pulmonary rehabilitation, post-pulmonary rehabilitation and at 6-month follow-up to test the impact of Internet-based CBT- I during home-based pulmonary rehabilitation on sleep and health-related functioning relative to home-based pulmonary rehabilitation only. We also examine whether sleep mediates the effects of treatment on health- related functioning.