The purpose of this study is: (1) to report the prevalence of vigorous physical activity and walking for exercise among a population-based sample of adults residing in Seoul; and (2) to determine the demographic predictors for vigorous physical activity and walking for exercise among these adults. Telephone interviews were administered to 248 male and 252 female adults residing in households in metropolitan Seoul using random digit dial procedures and stratification by gender. Multivariate analyses investigated differences in exercise by age, education and marital status. Males participated in vigorous exercise more than females, and married males were less likely to engage in vigorous exercise than non-vigorous physical activity. Males, older persons and unmarried males also spent more time engaged in vigorous exercise than females, younger persons, and married males. Participants with a high concern for health walked for exercise more than those with less concern. The amount of time spent walking for exercise was positively related to age. There is little information available about the causes of exercise habits among specific Korean subgroups. Our results suggest that cultural contingencies may operate differently by gender, a hypothesized moderator of exercise. Social contingencies, such as marriage, may interact with these gender and cultural differences. Future studies of health behaviors should include questions to measure social and cultural contingencies to understand the underlying, motivating theoretical processes.