The environmental causes of lung cancer have been the focus of intense epidemiologic and other research for > 50 years. The resulting evidence causally associates lung cancer with active and passive smoking, a variety of occupational agents, and indoor and outdoor air pollution. These causal associations have motivated control initiatives through education, regulation, and litigation. In recent years, the research focus has shifted to identifying the determinants of susceptibility to these agents, including interactions among environmental factors and genetic determinants of susceptibility to these agents. This article provides an overview of past and current research on the environment and lung cancer, and addresses the use of scientific evidence in controlling this cancer, which is largely caused by the environment.