This study describes the passive smoking histories of 380 never smokers who participated in a study on the respiratory health effects of tobacco smoke exposure conducted at a cancer screening clinic in Buffalo, New York, in 1986. Subjects were asked to report on their exposure to tobacco smoke during childhood years at home, as an adult at home, and as an adult at work. A total of 73 and 67% of subjects reported at least one year of continuous exposure to tobacco smoke at home as a child and as an adult, respectively. A total of 87% of subjects reported exposure to tobacco smoke at work. Subjects under age 40 years were more likely to report exposure to tobacco smoke at home as a child than were subjects aged 40 and older. Males and females differed in their reported exposure to tobacco smoke at home during adult years, with females reporting nearly twice as much exposure. Adult exposure at home also varied with age, with female subjects over age 55 years more likely to report having lived with other smokers. Age-adjusted correlations between childhood, adult home, and workplace exposure measures revealed little association between reports of exposure during different life stages. This study also evaluated concordance between subjects' exposure reports and those of surrogates who were asked to report on the subject's exposure at home, at work, and during childhood. Results showed good agreement between subjects and surrogates on most exposure measures. The results of this study underscore the need to obtain a complete exposure history from subjects when attempting to represent lifelong passive smoke exposure.