For more about the East-West Center, see http://www.eastwestcenter.org/ASEAN has been deepening intra-regional integration at the same time that it has been forming various cooperative arrangements with its partners, and its Member Countries have been pursuing individual trade accords. Which would be the optimal configuration for ASEAN? In this paper, we evaluate various economic scenarios for the region in terms of real-sector, financial, and macroeconomic cooperation with a view to gauge the best unit of integration. We review the current evolution of trade and financial accords in the region and survey the literature on the economic viability of these accords, including some fresh CGE simulations on the correlation of business cycles and...