Reducing perceptions of illness intrusiveness may improve quality of life and mental health among patients with cardiopulmonary disease. To better understand relationships between coping style, locus of control, perceived illness intrusiveness, and disease severity, we analyzed data from 227 older Veterans with chronic obstructive pulmonary disease or congestive heart failure. Regressions revealed illness intrusiveness to be associated with younger age and greater disease severity, less internal locus of control, and avoidant/emotion-focused coping. Avoidant/emotion-focused coping but not active coping mediated the relationship between illness severity and illness intrusiveness. Findings suggest that supportive psychological interventions may reduce illness intrusiveness by targeting an avoidant/emotion-focused coping style and associated behaviors.