This chapter considers drivers of regionalism and integration, focusing on Asia and Europe. It attempts to comprehend the factors that lead to regionalism and those that help to sustain it. It considers whether differing types of regionalism or integration are comparable and whether there are core design principles that are essential to regional communitybuilding. It argues that the essential driver in creating, or belonging to, a regional community is the recognition of the importance of two related factors: trust and reconciliation. Although the study of comparative regional integration has, at times, been characterised by a focus on the experience of the EU as the most advanced form of regional integration, it is in Asia that debates on regional architectures have been particularly vibrant among scholars and policymakers recently.1 The regional bodies that are located in Asia, range from the ASEAN; the ASEAN+3 (ASEAN plus China, Japan and South Korea); the EAS; the ASEAN Regional Forum (ARF ) and the Asia Pacific Economic Cooperation forum (APEC). In addition, Asia is home to initiatives for the Regional Comprehensive Economic Partnership (RCEP) and the TPP. The pivot by the United States, Australia and, to an extent, the EU, to the Asia-Pacific is also an opportunity to assess regional design and drivers of regionalism and integration.