Region-building is a significant form of transnational collective action to pursue social policy goals. It is an integral feature of the contemporary social policy and development landscapes, and of global governance. The EU often attracts most attention in the social policy literature but a wide range of regional formations worldwide are directly relevant to social policy and development As this chapter shows, world-regional policy is by no means confined to regional trade and investment agreements, or to economic development strategies, and regional cooperation, coordination and integration strategies extend across a very wide range of social sectors. Diverse regional-level social policy mandates, competences, programmes of action, monitoring and enforcement mechanisms are at work across different regional groupings around the world. The impetus behind a reformed system of global governance built on stronger regions that is linked to achieving the Sustainable Development Goals faces major challenges. The prevailing regional development paradigm presents obstacles to regional groupings’ abilities to develop coherent socially-inclusive development strategies. There is significant scope for research capable of incorporating regionalist development strategies into social policy and development studies literatures.