Today's fragmented world demands creative institutional arrangements to allow governments, international organizations and civil society actors to address transboundary and international problems. This article examines if and how the Global Environment Facility (GEF) can serve as a testing ground to find new ways to address such global problems in multilateral cooperation. After outlining the GEF's history, institutional setting and participatory elements, the paper points out some of its crucial weaknesses and flaws, such as insufficient private sector involvement, and the problem of power asymmetries. At the same time, however, the GEF can serve as a role model for international cooperation in many ways. More than any other international agency, the GEF is able to adapt to a constantly changing environment. The governance system of the GEF brings together advantages of both the UN and the Bretton Woods institutional rules and cultures. And it has a strong participatory element that includes close cooperation with nongovernmental actors.