This book challenges the proposition that regional organizations across the world exhibit increasing similarities with the European Union as a result of norm diffusion. It examines how and to what extent Indonesian foreign policy stakeholders—the government, civil society, legislators, the academe, the press and business representatives—sought to influence reforms of Southeast Asian regionalism by adopting ideas and norms of regional integration championed by the EU. Triggering the Indonesian debate on regionalism was the decision of the Association of Southeast Asian Nations (ASEAN), of which Indonesia is a founding member, to draft an ASEAN Charter, a quasi-constitutional document adjusting the grouping’s repository of cooperation norms to a changing international environment. Applying and developing further Amitav Acharya’s theory of “constitutive localization,” the analysis of the ASEAN Charter debate shows that—to varying degrees—Indonesian foreign policy stakeholders transfer the terminology of European integration to ASEAN’s organizational structure, but that they adopt only partially, if at all, the normative substance of the EU model for regional integration. Instead, they skillfully reconcile alien norms with local norms, with the effect of retaining what could be called an Indonesian way of foreign policy-making.