The National Environmental Policy Act (NEPA), which was signed into law on January 1, 1970, has come to be regarded as the first major piece of federal legislation to call for comprehensive attention to environmental concerns in the United States. During the two decades following enactment of NEPA, Congress adopted and then refined major legislation on nearly every aspect of environmental quality concerns: air pollution, water pollution, drinking water quality, hazardous waste management, wildlife protection, pesticide use, and several related problem areas. Current arguments for environmental regulatory reform are a phase in the continuing evolution of this body of federal environmental policy.