This volume documents the proceedings of the U.S. Environmental Protection Agency-sponsored symposium 'Tumor Promotion and Enhancement in the Etiology of Human and Experimental Respiratory Tract Carcinogenesis,' held in Williamsburg, VA in June 1984. In order to determine the necessity to monitor enhancers/promoters in the environment, or even to decide whether there is a role for these agents in the etiology of human lung cancer, the available evidence must be reviewed, assimilated, and correlated in epidemiologic studies, and studies with experimental animals. The contributors to this volume seek not only to identify chemical agents but also seek to cover biological processes and pathologic conditions of infectious and non-infectious origin that may have been shown to predispose to the development of lung cancer.