Trends in cigarette smoking among successive cohorts of men and women were reconstructed from smoking histories of respondents to the 1978-80 Health Interview Surveys. Estimated smoking rates among the older cohorts were then adjusted for the differential mortality of cigarette smokers and nonsmokers. By 1920, over half of the young male population smoked cigarettes. Not until 1950 did more than a third of the young female population smoke cigarettes. The proportion of men who ever smoked cigarettes progressively declined with each successive cohort born after 1920. By contrast, the proportion of women who ever smoked declined only among cohorts born after 1940. Cessation of cigarette smoking from age 30 years onward was observed for all cohorts of men. Cessation rates accelerated for men who reached age 30 after 1960. By contrast, smoking cessation from age 30 was observed only for women who reached age 30 after 1950. Cessation rates accelerated only for women who reached age 30 after 1970. For each cohort, recent smoking cessation rates for men have exceeded those for women. Maximum exposure to cigarette smoking probably occurred among men who are now in their seventh and eighth decades. By contrast, peak exposure to smoking probably occurred among women who are now only in their fifth and sixth decades.