Have environmental values become part of the normative structure of international society? Has the rise of global environmentalism led to a greening of international society? Most International Relations research on environmental issues fails to address these questions as it typically focuses on the creation of issue-specific regimes or informal governance mechanisms. This article engages English School theory in an effort to examine the impact that global environmentalism has had on the social structure of International Relations. It argues that a primary institution of global environmental responsibility is emerging, and explores the relationship and tensions between environmental responsibility and the established primary institutions of sovereignty, international law and the market.