This article discusses environmental policy integration—a concept so far mainly applied to domestic and European politics—at the global level. The article distinguishes between integration of institutions, of organizations, and of their bureaucracies, and it addresses both internal integration (within the environmental policy domain) and external integration (between environmental policies and non-environmental policies). The overall focus is on one set of policy reform proposals that have been salient in the global environmental governance debate for the last decades: the question of whether the creation of a world environment organization would improve the effectiveness, legitimacy, and efficiency of global environmental governance. We revisit this debate and explore the options for organizational change, including clustering, upgrading, streamlining, and hierarchical steering, with a focus on whether the reform proposals can bring about environmental policy integration. We conclude that in the longer term, upgrading of the UN Environment Programme to a UN specialized agency, with additional and increasing streamlining of other institutions and bureaucracies, offers the most potential for environmental policy integration and does not appear to be unrealistic.