There is a dearth of studies exploring the construction of ideas on regionalism outside Europe. This article seeks to make a contribution to close this gap. It examines the construction of ideas on regionalism in Indonesia, the largest member country of the Association of Southeast Asian Nations (ASEAN). Theoretically, the paper draws from Acharya's concept of “constitutive localization” which it develops further. It offers an alternative explanation to studies which argue that as a result of mimetic behavior, social learning, and cost-benefit calculations, regional organizations across the world become increasingly similar. While this may be the case in terms of rhetoric and organizational structure, it is not necessarily the case at a normative level. The Indonesian case shows that even though foreign policy stakeholders have increasingly championed European ideas of regional integration after the Asian Financial Crisis of 1997/1998, they have skillfully amalgamated them with older local worldviews through framing, grafting, and pruning. European ideas of regional integration thereby served to modernize and relegitimize a foreign policy agenda which seeks to establish Indonesia as a regional leader with ambitions to play a major role in global politics.