This chapter explores the theory and practice of environmental protection in the United States (U.S)?s multi-layered federal system. A brief general overview of the federal system of government sets the stage for a detailed discussion of the role federalism plays in environmental protection in the U.S. The chapter focuses on examples taken primarily from the statutory programs controlling water pollution, but also describes the programs for controlling pollution in other media. Issues to be explored include the uncertain scope of federal jurisdiction over environmental resources, the joint role State and federal actors play in developing pollution limitations and in implementing environmental statutes, and the role of the public engagement in environmental programs. Empowering public participation in environmental governance has been described by one scholar as ?essential to our democratic experiment?.  Keywords:environmental governance, environmental protection, federalism, multi-layered federal system, United States