This study examines the role of unions in implementing the Occupational Safety and Health Act (OSHA) by using a data set that provides information on regulatory enforcement. The analysis demonstrates that unionized establishments are more likely to receive safety and health inspections, face greater scrutiny in the course of those inspections, and pay higher penalties for violating health and safety standards than comparable nonunion establishments. Implementation of OSHA therefore seems highly dependent upon the presence of a union at the workplace.