The slowdown in productivity growth in the U.S. economy during the 1970’s has been a matter of great concern to policymakers, associated as it is with inflation, unemploy­ ment, and declining real wage growth. This paper examines the impact on productivity growth of government regulation, specifically worker health and safety regulation by the Occupational Safety and Health Administra­ tion (OSHA) and environmental regulation by the Environmental Protection Agency (EPA). Looking at data for 450 manufactur­ ing industries between 1958 and 1978, the study finds a large, negative relationship between such regulation and productivity growth. Using these results, about 30 percent of the decline in productivity growth in manufacturing during the 1970’s may be at­ tributed to such regulation.