International governance increasingly occurs through complex synergies between networks of actors across levels of international politics. This volume describes and analyzes the activities of many new actors in the realm of sustainable development. It highlights their activities and challenges, as well as critiques of their role in international governance. At the same time, the authors raise new theoretical and empirical questions for the future study of globalization and the formulation of policies for global issues. While states ultimately continue to make and enforce international law, they are increasingly dependent upon multilateral institutions, organized science, NGOs and social movements, and business and industry for formulating their views and conducting policy. This volume focuses on clarifying the key actors and the governance functions they perform in addressing environmental threats.