This paper presents results from a preliminary short-term work-site intervention study aimed at smoking cessation. The 3-month intervention included consultation for employers on the adoption of a nonsmoking policy, training for nonsmokers to provide assistance to smokers attempting to quit, and cessation classes for smokers. Eight work sites from Bloomington, Minnesota were recruited to the study and randomly assigned to an intervention or comparison condition after a baseline survey of all employees. To assess the effect of the intervention, smokers were surveyed 1 and 6 months after the intervention was completed. At the 1-month follow-up, the overall quit rate in the intervention group was 12% compared to 5% in the control group (P < .05). At the 6-month follow-up, 12% of smokers in the intervention group reported quitting, compared to 9% in the control group (P < .05). Co-worker support for quitting was higher in the intervention group compared to the comparison group. Cessation was highest overall among smokers whose co-workers frequently asked them not to smoke and among those who worked with a high proportion of nonsmokers. These results indicate that a short-term, multifaceted smoking cessation program implemented in work sites can affect smoking cessation rates as well as the work-site norms about smoking.