This chapter will explore the relevancy of the Fukuda Doctrine to communitybuilding in East Asia. I argue that the Doctrine laid the foundation for healthy Japan-ASEAN relations, underpinned by economic interdependence and the norms of a “heart-to-heart” relationship. Such solid ties have become the basis for East Asian Community-building in which both Japan and ASEAN play crucial roles. Japan, on the one hand, is the most advanced country in East Asia which possesses the highest capability in contributing to regional integration. The production networks through Japanese foreign direct investment (FDI) are the impetus toward East Asian regionalism, particularly in terms of economic partnership agreements (EPAs) and monetary cooperation. ASEAN, on the other hand, provides a venue and norms for regional cooperation, as it is the sole viable organization in the region. Accordingly, Japan and ASEAN have been working together to bring about both conditions and mechanisms for East Asian regionalism.