Pulmonary fibrosis that develops within a subpopulation of patients with rheumatoid arthritis is a disorder of unknown etiology. Although previous reports suggest that some individuals with rheumatoid arthritis have a genetic predisposition to the development of fibrotic lung disease, genetic factors have not been clearly identified. It is the intent of this clinical protocol to identify genetic polymorphisms in individuals with pulmonary fibrosis and rheumatoid arthritis.