Patients with connective tissue disease (CTD) account for a large proportion of patients with interstitial lung disease, and another group with many similar features but not overt CTD are subsumed under the heading of “interstitial pneumonia with autoimmune features (IPAF).” Pathologic findings suggestive of CTD-ILD or IPAF include numerous lymphoid aggregates, lymphoid aggregates with germinal centers, interstitial inflammation with a high proportion of plasma cells, a picture of NSIP plus organizing pneumonia, a fibrotic and thickened pleura, and rheumatoid nodules. Identification of CTD-ILD features is important because such patients are generally treated with immunosuppression.