Alberto Alesina is Nathaniel Ropes Professor of Political Economy and currently Chairman of the Department of Economics at Harvard University, and has been Visiting Professor at IGIER-Bocconi and MIT. He is a Research Associate for the National Bureau of Economic Research and for the Center for Economic Policy Research. He is coeditor of the Quarterly Journal of Economics, and in addition to his many books and scientific papers he has published columns in the Financial Times, the Wall Street Journal Europe, Le Monde, Il Sole 24 Ore, Corriere della Sera, La Stampa, Frankfurter Zeitung, Handelsblatt, and many other newspapers world wide. Edward Glaeser is a Professor of Economics at Harvard University, where he has taught since 1992. He teaches urban and social economics and microeconomic theory, and has published dozens of papers on cities, economic growth, and law and economics. He is a Research Associate for the National Bureau of Economic Research, and has also been a consultant for numerous international institutions.