This is the second report of the U.S. Surgeon General devoted to women and smoking. The first was published in 1980 (U.S. Department of Health and Human Services [USDHHS] 1980), 16 years after the initial landmark report on smoking and health of the Advisory Committee to the Surgeon General appeared in 1964 (U.S. Department of Health, Education, and Welfare [USDHEW] 1964). The 1964 report summarized the accumulated evidence that demonstrated that smoking was a cause of human cancer and other diseases. Most of the early evidence was based on men. For example, the report concluded, "Cigarette smoking is causally related to lung cancer in men.... The data for women, though less extensive, point in the same direction" (USDHEW 1964, p. 37). By the time of the 1980 report, the evidence clearly showed that women were also experiencing devastating health consequences from smoking and that "the first signs of an epidemic of smoking-related disease among women are now appearing" (USDHHS 1980, p. v). The evidence had solidified later among women than among men because smoking became commonplace among women about 25 years later than it had among men. However, it was still deemed necessary to include a section in the preface of the 1980 report titled "The Fallacy of Women's Immunity." In the two decades since, numerous studies have expanded the breadth and depth of what is known about the health consequences of smoking among women, about historical and contemporary patterns of smoking in demographic subgroups of the female population, about factors that affect initiation and maintenance of smoking among women (including advertising and marketing of tobacco products), and about interventions to assist women to quit smoking. The present report reviews the now massive body of evidence on women and smoking-evidence that taken together compels the Nation to make reducing and preventing smoking one of the highest contemporary priorities for women's health.