This briefing paper uses data collected by the U.S. Bureau of Labor Statistics, the Centers for Disease Control and Prevention, and the U.S. Census Bureau to evaluate costs and benefits of Chicago’s Earned Sick Time Ordinance. It estimates how much time off Chicago workers would use under the proposed policy and the costs to employers for that earned sick time. This analysis also uses findings from previous peer-reviewed research to estimate cost-savings associated with the proposed policy, through reduced turnover, reduced spread of contagious disease in the workplace, prevention of productivity losses from employees working while sick, minimized nursing-home stays, and reduced norovirus outbreaks in nursing homes. The study is one of a series of analyses by IWPR examining the effects of earned sick time policies.