Strategies aiming to foster social cohesion seek to enhance predictability and trust among heterogeneous actors. Although undoubtedly nation-states remain the dominant context for examining social cohesion, in Europe and in South America, nation-states have formed regional organizations to support political stability and economic cooperation in a world increasingly shaped by political and economic forces beyond the reach of any single nation-state. The comparative extent to which the regional political bodies of the European Union (EU) and the Southern Common Market (MERCOSUR) impact social cohesion within and across member states relates to their capacity to engender reciprocal patterns of political stability and economic development in the region. This article examines the EU and MERCOSUR's stake in social cohesion and how these organizations impact social cohesion in their respective regions through the establishment of institutionalized standards and norms, the content of specific regional policies, and the processes that accompany institutional governance at the regional level. The article finds that the existence of collective support and trust in the institutions that enable these regional organizations to effectively create desired political and economic conditions has implications for the depth of these integration projects and their ability to foster social cohesion across a region. (Contains 1 footnote.)