This chapter focuses on national law, while also introducing international and European sources. Environmental law emerges at international, European, and national levels partly because the complex, interconnected nature of environmental problems requires a range of solutions at all of these levels. Some of the key characteristics of environmental laws that help to explain both the form and function of UK environmental law are examined here. The chapter also considers the institutions that are involved in the administration of environmental law and policy. The administration of environmental law and policy is carried out by a diversity of bodies, including government departments, regulatory agencies such as the Environment Agency, and a range of quasi-governmental bodies. The focus here is almost exclusively on UK structures and institutions. An underlying theme of the chapter is the way in which administrative structures are used to encourage the integration of environmental law and policy both internally—for example, through the creation of the Environment Agency as a unified regulatory agency—and externally; for example, through various methods of scrutinizing environmental policy across government departments.