Since the financial crises of 1997, East Asia has made modest but nonetheless significant steps towards greater regional integration and cooperation in the areas of finance and trade, accompanied by progress on institution-building at the regional level. Monetary cooperation, however, has not proceeded to anything like even the modest levels registered for other functional areas of cooperation. This paper investigates this discrepancy. It asks whether monetary cooperation is simply an unattractive proposition because it promises fewer net gains than cooperation on other issues, or whether there are other explanations for the absence of monetary cooperation in the region. Based on a review of estimates of the aggregate economic gains and losses arising from monetary cooperation, the paper argues that there is a prima facie puzzle to be explained: monetary cooperation does hold out the prospect of real gains and, although these gains are not cost-free, neither is the status quo. The paper then turns to the domestic level of the major East Asian countries, in order to assess the relative strength of the domestic economic interests that are likely to be either advocates or opponents of monetary cooperation. It shows that domestic distributional politics - the processes by which gains and losses within countries are distributed - are a plausible reason for the low priority placed on regional monetary cooperation to date. International-level political concerns and the potential supply of institutional solutions to collective action problems are additional reasons for the lack of monetary cooperation, but the domestic demand for such cooperation is analytically prior to these more conventional explanations for the lack of cooperation in East Asia.