The recent financial crisis and the difficulty of using mainstream macroeconomic models to accurately monitor systemic risk have stimulated new analyses of how we measure economic activity and the development of more sophisticated models in which the financial sector plays a greater role. Markus Brunnermeier and Arvind Krishnamurthy have assembled contributions from researchers, central bankers, and other financial-market experts to explore the possibilities for advancing macroeconomic modeling in order to achieve more accurate measurement. Essays focus on the development of models capable of highlighting the vulnerabilities that have never been systematically measured before.