The introduction of a single European currency constitutes a remarkable instance of internationalization of monetary policy. Whether a concomitant internationalization can be detected also in the econometric foundations of monetary policy is the problem dealt with in this book. Its basic theoretical ingredients comprise a data-driven approach to econometric modelling and a generalized approach to cross-sectional aggregation. The resulting econometric model systematically combines statistical and economic theory by extending a cointegrated VAR into a structural ECM. The empirical outcome is a data-consistent causal money demand function, isolated within a properly identified dynamic macroeconomic system for Europe.