This chapter examines the environmental law of the European Union. It first provides an overview of the early development of EU environmental law and its Treaty bases before discussing the structure and substance of EU environmental law. In particular, it considers both the transversal elements of environmental law (environmental principles, access to information and justice, environmental impact assessment, principles of liability) and its regulation of various areas such as chemicals/waste, water, conservation, air pollution, and climate change. It also explores the EU’s indirect and other influences on the environmental law of its Member States, as well as the implementation framework for the EU environmental law. The chapter concludes with an analysis of the administration of European environmental law, with emphasis on the role of Member States in administrative enforcement and the role of the Court of Justice of the European Union in the development of environmental policy across the EU.