This article examines whether states shirked enforcement responsibilities in their principal-agent relationship with the federal government when implementing a delegated environmental program. It evaluates determinants of environmental enforcement stringency, particularly whether penalties were less when imposed by states than by the federal government. It analyzes 6,048 hazardous waste administrative penalties across 32 states and all U.S. Environmental Protection Agency Regions over 14 years. It finds that state penalties are typically substantially lower than federal penalties, and that penalty amounts are typically also related to the partisan composition of elected officials and the characteristics of enforcement actions, such as the type, seriousness, and number of violations. Factors such as the influence of organized interest groups, agency sensitivity to economic conditions or the economic importance of regulated industries, and environmentalist preferences of elected officials and the public are typically unrelated to enforcement stringency.