Subjects are being asked to participate in a research study that is investigating the way the lung is damaged in a condition called pulmonary fibrosis. These research studies are conducted in the laboratory on a portion of the tissue from the subject's lung biopsy that was performed by a surgeon. The lung biopsy is to be performed for clinical purposes to diagnose the cause of the subject's lung disease. The tissue used for the research study will in no way interfere with the ability of the pathologist to establish a diagnosis. In addition, the results of your breathing tests, chest X-rays and CT scans, and diagnosis made from the lung biopsy (and slides) will be collected. The goal of the study is to gain an understanding of the causes of pulmonary fibrosis and why it gets worse, which may ultimately lead to new therapies for this disease. Once the lung biopsies are obtained, the pathologist will examine the tissue and determine if there is a sufficient amount available to use in the study without compromising their ability to make a diagnosis. If so, the lung biopsy will be divided. One portion will be submitted to the research study and the other processed by the pathologist in the usual manner to make a diagnosis. The decision to use tissue for the research study will be at the complete discretion of the pathologists. The tissue used in the study will be further processed in the laboratory in order to analyze for the presence of genetic markers in the scarred tissue that are not present in normal. The identification of these unique genetic markers of scarred lung may ultimately lead to new approaches to the diagnosis and treatment of pulmonary fibrosis.