Chronic obstructive pulmonary disease (COPD) continues to cause a heavy health and economic burden around the world. Recent studies have added evidence to the etiologic role of known and suspected risk factors for lung function decline and COPD, including smoking, occupational exposures, air pollution, airway hyperresponsiveness, and certain genetic variations. Among most populations, COPD prevalence and mortality are still increasing and will likely continue to rise in response to increases in smoking, particularly by women and adolescents. Resources aimed at smoking cessation and prevention and the early detection of COPD will be of the most benefit in our continuing efforts against this important cause of morbidity and mortality.