Alberto Alesina is Nathaniel Ropes Professor of Political Economics at Harvard University. Olivier Blanchard is Professor of Economics at MIT. Jordi Gali is the Director of the Centre de Reccera en Economia Internacional (CREI) and a Professor of Economics at Universitat Pompeu Fabra (Barcelona). He is co-director of CEPR's International Macroeconomics Programme and an NBER Research Associate. Francesco Giavazzi is is professor of economics at Bocconi university in Milan and a Regular Visiting Professor at the Massachusetts Institute of Technology (MIT). Harald Uhlig is Professor of Economic Policy at Humboldt Universitat zu Berlin and a Research Fellow in CEPR's International Macroeconomics and Financial Economics research programmes.