This article focuses on how subnational governments try to be part of the global sustainable development debate. In particular, it looks at the Belgian subnational government of Flanders and decision-making in the UN Commission on Sustainable Development. Subnational entities, such as Flanders, are not directly represented in global multilateral organizations and thus need to fi nd other ways if they want to be involved. Yet, those organizations play an important role, for example with regard to agenda-setting and the formulation of global sustainable development goals. Starting from a multi-level governance perspective, we use a typology of four routes, along the dimensions intra-and extra-state and intra-and extra-European, that subnational governments have at their disposal. In each of those routes multiple interactions take place between different levels of government. We show that the Flemish government has most extensively used intra-state routes, fi rst and foremost because of the constitutional opportunities it has within the Belgian institutional context. Extra-state routes that bypass the state are used less, because greater access is possible through the state and because those routes require a higher investment in fi nancial and human resources. A direct consequence of the use of the intra-state routes is the important role that has to be ascribed to the interactions between the Flemish and the federal level of government. Those interactions are steered by specifi c intra-Belgian arrangements and shape how Flanders can be involved.