Abstracts -- Introduction -- 1 The Source of Historical Economic Fluctuations: An Analysis using Long-Run Restrictions -- Comment Harald Uhlig, Humboldt Universität zu Berlin, Tilburg University, Bundesbank, and CEPR -- 2 Optimal Monetary and Fiscal Policy in a Liquidity Trap -- Comment Tor Einarsson, University of Iceland -- 3 Rule-Based Monetary Policy under Central Bank Learning -- Comment Fabio Canova, ICREA-Universitat Pompeu Fabra, CREI, AMeN, and CEPR -- 4 The Comovement of Returns and Investment within the Multinational Firm -- Comment José Manuel Campa, IESE Business School -- 5 How Do Monetary and Fiscal Policy Interact in the European Monetary Union? -- Comment Gauti B. Eggertsson, Federal Reserve Bank of New York -- 6 Does it Cost to be Virtuous? The Macroeconomic Effects of Fiscal Constraints -- Comment Kenneth D. West, University of Wisconsin and NBER -- 7 Can Endogenous Changes in Price Flexibility Alter the Relative Welfare Performance of Exchange Rate Regimes? -- Comment Gianluca Benigno, London School of Economics, CEP, and CEPR -- 8 Saving and Cohabitation: The Economic Consequences of Living with One's Parents in Italy and the Netherlands -- Comment Mihir A. Desai, Harvard University and NBER -- 9 Is Poland the Next Spain? -- Comment Jeffrey A. Frankel, Harvard University and NBER.