Chronic obstructive pulmonary disease (COPD) is a preventable and treatable disease that causes a heavy health and increasing economic burden both in the United States and around the world. Most of the risk factors for COPD are well known and include smoking, occupational exposures, air pollution, airway hyperresponsiveness, asthma, and certain genetic variations, although many questions, such as why a minority of smokers develop significant airway obstruction, remain. Major medical organizations have agreed on a common definition of COPD, although newer measures, such as functional status or exercise capability, have emerged as important in determining the prognosis of COPD patients. In most of the world, 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, COPD education and early detection, and better treatment will be of the most benefit in our continuing efforts against this important cause of morbidity and mortality.