Overall exposure to secondhand smoke at work across Missouri is 11.5%. However, among young white men with low incomes and limited education living in small rural areas, 40% of nonsmokers and 56% of smokers may be exposed to secondhand smoke at work. On the basis of our model, the highest exposure category is smokers who were young black men making less than $15,000 a year with less than a high school education and living in isolated areas. This group has a 66% chance of being exposed to secondhand smoke in the workplace. This same group with nonsmoking status would have a 50% chance of exposure based on our model.Missouri is one of 27 states without a comprehensive smoke-free workplaces law.