Patterns of prevalence, amount, and cessation of smoking are computed for occupations by socioeconomic class, sex, and race, based on a probability sample of 39,011 households collected by the 1970 Health Interview Survey. Smoking is most prevalent in blue-collar occupations, while a high proportion of professionals and managers who smoke, stop smoking. Within industries, substantially higher percentages of individuals smoke in lower prestige paying jobs, while more smokers quit in the higher prestige paying jobs. Smoking is most prevalent among women managers and professionals, and least among those employed in traditional work. One surprising and possibly very important finding is that white smokers smoke about 20% more cigarettes per day than black smokers. Not only would it seem unreasonable to ascribe the larger rate of lung disease among blacks than whites (especially cancer), to smoking when blacks smoke significantly fewer cigarettes than whites, but this same negative relationship points to occupational exposure as the possible major cause for lung cancer.