This chapter provides an overview of US and European Union (EU) environmental policy initiatives at both the domestic and the international level. It examines the outlook of US and EU environmental postures, assessing the future prospects for transatlantic environmental governance. The increasing reluctance to commit to international environmental agreements became apparent when the United States failed to join the 1992 Convention on Biological Diversity (CBD). The Barack Obama administration has pledged renewed attention to the environmental cause, promising to re-establish US leadership on climate change. In both the US and the EU, environmental policies have experienced a remarkable evolution over the last three decades. The chapter provides an overview of this transformation by focusing on four key policy areas where the divergence between the US and the EU has emerged more sharply, namely the countering of climate change, the protection of biodiversity, the promotion of renewable energies and the pursuit of sustainable development.