This article offers a survey of the literature on European Economic and Monetary Union (EMU), in particular works that deal with the question why EMU happened and, based on this literature, what one might be able to conclude about its sustainability. It reviews the literature by dividing up the analyses into four categories: those that explain EMU at the global and at the European Union (EU) levels of analysis, explanations at the national level, and explanations at the domestic level of analysis. The review suggests that EMU was a particular European response to global developments, which was possible because of existing EU institutions. EMU was causally motivated by a Franco-German deal, balancing national interests. Domestic motives reflect essentially opportunistic motives, and thus, cannot explain EMU. In our judgment the review suggests that Europe's single currency will remain sustainable as long as the Franco-German political deal sticks, the belief in the "sound money" idea remains hegemonic in Europe, and the losers from EMU are underrepresented in national and EU institutions. While opportunistic domestic motives cannot explain embarking on a long-term project, they can definitely be sufficient to derail such a project.