Plans for the European Monetary Union (EMU) are based on the conventional postulate that increasing the independence of the central bank can reduce inflation without any real economic effects. However, the theoretical and empirical bases for this claim rest on models of the economy that make unrealistic information assumptions and omit institutional variables other than the central bank. When signaling problems between the central bank and other actors in the political economy are considered, we find that the character of wage bargaining conditions the impact of central bank independence by rendering the signals between the bank and the bargainers more or less effective. Greater central bank independence can reduce inflation without major employment effects where bargaining is coordinated, but it can bring higher levels of unemployment where bargaining is less coordinated. Thus, currency unions like the EMU may require higher levels of unemployment to control inflation than their proponents envisage. They will have costs as well as benefits, and these will be unevenly distributed among and within the member nations, depending on the changes they induce in the status of the bank and of wage coordination.