Federal, state, and local governments are major polluters of the environment. They account for more than 7% of SO2 air pollution emissions and more than 5% of all NO2 air emissions in the United States. Public entities are more likely than private ones to be in violation of the Clean Water Act, and they account for two-thirds of all major facilities in significant noncompliance with the act. Department of Energy nuclear sites are the worst hazardous waste problems in the nation. A lack of adequate data makes it difficult to fully characterize the extent of pollution caused by government agencies and to compare the performance of the public and private sectors. There are many reasons why government pollution is difficult to regulate. The paper discusses political dimensions, legal problems, resource constraints, psychological dimensions, and public opinion. Further research is urgently needed, and the paper delineates areas that require more investigation.