The author aims to contribute her views about the relationship between regional powers and the integration process in East Asia, arguing that the interests of powerful states would determine the nature, dynamics and directions of the East Asian Community-building process. The term ``regional powers`` used in the paper refers to China and Japan, the two Northeast Asian powerful states. The paper consists of three parts. From historical and theoretical perspectives, the paper discusses the concept of regionalism in East Asia and the idea of the East Asian Community that the regionalism-making process in East Asia is gearing to, highlighting the increasing role played by China and Japan. Next, the paper focuses on the analysis of changes in the perceptions held and policies pursued by China and Japan toward the building of the East Asian Community and regional integration at large. Lastly, based on the analysis, the paper envisions the future roles by China and Japan to the building of an East Asian Community.