The chapter analyses the exchange rate regimes adopted in East Asia since the 1990s and the future of monetary cooperation in this area where new issues are raised with the increasingly important role of China. Using a FEER approach, exchange rate misalignments are estimated and appear more limited in East Asia in the current period than during the 1990s, thanks to more pragmatic exchange rate regimes, in clear contrast with what has been observed in the euro area. To investigate more precisely the past and future exchange rare regimes, a four-country Stock Flow Consistent model with China, Japan, East Asia and the rest of the world is proposed. The great heterogeneity of the whole East Asia, both in terms of level of development and of countries’ size, pleads for keeping an adjustable exchange rate system in the future monetary regime, at least for a long transition period. The ACU (Asian Currency Unit) regimes or a pragmatic yuan block, thanks to the possibility of exchange rate adjustments, appear as possible trade-offs.