Cigarette smoking cessation and resumption patterns are presented from biennial examination data from the Framingham Study for the years 1956-1978. At 22 yr of follow-up, 68% of men and 53% of women stated they had stopped smoking for at least 1 year. Younger participants had lower cessation rates than older, and those who smoked more cigarettes per day had lower cessation rates than those who smoked fewer. Lower cessation rates were found in men who drank alcohol, and in women who drank coffee, were leaner, or were of lower education. Resumption of cigarette smoking after nonsmoking for at least 1 year occurred in 35% of women and 25% of men over 20 years of observation. Most resumption occurred in the first 4 years after quitting. Men who smoked a greater number of cigarettes prior to quitting were observed to have a smaller probability of resumption. This latter finding is paradoxical and needs confirmation from other studies.