The Occupational Safety and Health Act of 1970 (OSHA) regulates conditions in private sector establishments and has been one of the most controversial examples of social regulation of the past two decades. On the one hand, OSHA has been charged with imposing needlessly high costs on firms. On the other hand, the relative stability in the overall incidence of workplace injuries in the last two decades since OSHA's passage suggests that it has had a negligible impact on safety and health in the workplace. Yet, only a very limited amount of independent, empirical research has been completed to date to link the enforcement efforts of OSHA to health and safety in the workplace. This project fills an important empirical gap by analyzing the underlying determinants of OSHA performance. Specifically, this study draws upon a data set which contains the complete records for inspections conducted by OSHA from 1971 to June of 1991. The analysis is pursued in two stages. First, the study empirically examines the relationship between different levels of enforcement and firm-level compliance with specific health and safety standards. Second, it measures the relationship between compliance and health and safety outcomes, such as the incidence of workplace injuries. In addition to answering a number of questions concerning the efficacy of current methods of safety and health regulation, it advances general understanding of compliance behavior in enforcement based regulatory systems. While analyses to date typically assume perfect compliance with promulgated regulations, this study tests notions of regulatory performance from the perspective of limited enforcement and imperfect compliance.