In the early 1990s, APEC can be seen as a significant departure in Asia-Pacific regionalism. Yet, as the Asia-Pacific regionalism is till vague, East Asian regionalism based on institutional economic integration such as ”ASEAN plus N FTAs (ASEAN+1 and ASEAN+3)” has drawn plenty of attention since the late 1990s. More importantly, the development of East Asian economic integration has generated extensive impacts on APEC and its members as well as its relevance in the future architecture of the Asia-Pacific region. Under this circumstance, various concerns about the relationship between Asia-Pacific and East Asian economic cooperation have increasingly surfaced. In addition to examining the development of regional integration schemes in both Asia-Pacific and East Asian regions, this paper aims to explore the response of APEC and its members towards the regional architecture by identifying some critical issues and perspectives in this regard.