Over the last thirty years, the European Union has created a system of environmental governance in Europe. With a large number of legislative measures, the EU’s environmental policy is broad in scope, extensive in detail and often stringent in effect. Environmental governance also extends to the ways in which decision making on environmental policy has become institutionalized within Europe, both at the level of the EU itself and in the practices of the member states. This work seeks to understand this new system of environmental governance both at the European level and at the level of member states. It argues that the system is multi-level, horizontally complex, evolving and incomplete. Locating developments at the European level in theories of European integration, it goes on to examine the extent of convergence and divergence in environmental policy among six member states: Germany, Spain, Greece, Italy, the Netherlands, and the UK. It then looks at the operation of the system of environmental governance through an examination of policy case studies before examining the wider political significance of these developments.