AbstractA model of safety and of the impact of the Occupational Safety and Health Administration (OSHA) on safety in industrial firms is described in this article. The model incorporates safety feedback processes in U.S. manufacturing firms, including the relations between safety programs, safety equipment, and accidents. Monte Carlo‐like simulations were produced, with 1,000 firms simulated sequentially. The firms were distributed among the 20 standard industrial sectors and the five size categories that comprise the manufacturing industry. Each firm's safety behavior was simulated for a four‐year period, and each firm was inspected once by OSHA. Injury rates across all firms were measured to determine if OSHA's actions had a measurable effect upon safety in firms. The model captures important underlying assumptions regarding safety regulation that have typically been excluded from evaluations of the impact of safety regulation in the United States. These assumptions may in fact be central to understanding the relations between intervent