A very influential strand in comparative political economy has traced the Eurozone’s problems to the political-institutional factor of differing domestic wage bargaining institutions. The argument is that stronger wage bargaining coordination is more compatible with the single currency’s macroeconomic regime. The implication is that wage bargaining coordination will explain differing economic success within the Eurozone. This article empirically tests the observable implications of this theory by looking at the relationship between wage bargaining coordination and economic growth. A multitude of specifications analyzing the Eurozone sample (including the newer members) and the broader European Economic Area group, encompassing simple descriptive statistics, panel data analysis, and panel Difference-in-Differences models, fails to support the linear hypothesis. Instead, there is evidence for a curvilinear (hump-shaped) relationship whereby the medium level of coordination is linked to worst macroeconomic outcomes. Furthermore, the article shows how expanding the sample to include the newer members of the Eurozone can affect the discussion on the political-institutional prerequisites of successful performance under a single currency area.