The chronic lung diseases are those disorders associated with functional and/or structural derangement to the alveolar structures, airways, pulmonary blood vessels, pleura and/or mediastinum. The purpose of this project is to permit the comprehensive evaluation of patients referred to the Cardiovascular and Pulmonary Branch of the National Heart, Lung, and Blood Institute (NHLBI) in order to: (1) develop an understanding of the etiology and pathogenesis of these disorders; and (2) identify individuals who will be suitable candidates for other NHLBI protocols. Testing and procedures will only be performed when medically indicated for the purposes of making a diagnosis or obtaining information likely to be useful in the management of the subjects' disease or condition.