This cross-sectional study examined whether psychosocial factors at work were associated with smoking, sedentary behavior, and body mass index. The study population was composed of 3531 men and 3464 women employed as white collar workers in 21 organizations. Data were collected at worksites. Psychological demands and decision latitude at work were measured with the Karasek 18-item questionnaire. Smoking, sedentary behavior, and mean body mass index were compared by quartiles of decision latitude and psychological demands and by job strain categories. Prevalence of smoking, mean number of cigarettes smoked per day, prevalence of sedentary behavior, and mean body mass index were not consistently associated with decision latitude, psychological demands, or high job strain. However, prevalence of smoking was elevated in women belonging to the highest quartile of psychological demands (odds ratio [OR], 1.2; 95% confidence interval [CI], 1.0 to 1.6) and in the active job strain groups in both men (OR, 1.6; 95% CI, 1.2 to 2.1) and women (OR, 1.4; 95% CI, 1.0 to 2.0). Prevalence of sedentary behavior was elevated in men in the lowest quartile of decision latitude (OR, 1.3; 95% CI, 1.0 to 1.7), in the passive group (OR, 1.3; 95% CI, 1.0 to 1.5), and in the high strain group (OR, 1.2; 95% CI, 1.0 to 1.6). In women, this prevalence was elevated in the third quartile of psychological demand (OR, 1.3; 95% CI, 1.1 to 1.6). These results provide only partial support for an association between some psychosocial factors at work and the prevalence of smoking and sedentary behavior.