Introduction -- International regimes in a world of change : why legitimacy? -- What is, and how can we measure, the legitimacy of regimes? -- Non-state actors and the legitimacy of international regimes -- Regimes, case-design, and coding procedure -- Regimes and the reduction of uncertainties -- Regimes and compliance -- Regimes and the management of environmental problems -- Distributional consequences of environmental regimes -- Non-state actors and participation in regime polities -- C