Motivated by policy debates emerging from the U.S. Great Recession and Eurozone crisis, I study the stabilization role of monetary, fiscal, and macroprudential policies in response to short-run fluctuations. In the first essay on "Unemployment Insurance in Macroeconomic Stabilization", I characterize the role of unemployment insurance (UI) generosity as a particular instrument of fiscal policy, and use my framework to quantitatively evaluate the employment and welfare effects of UI extensions in the U.S. over 2008-13. In the second essay on "Labor Market Frictions in a Monetary Union", I study stabilization trade-offs and optimal monetary policy in a monetary union where labor markets are frictional and heterogeneous across member states, with implications for the sustainability of the Euro and policy of the ECB. In the third essay on "Firm vs. Bank Leverage over the Business Cycle", I develop a general equilibrium model explaining the contrasting cyclical behavior of non-financial corporate and bank leverage in U.S. data, and study its implications for macroprudential regulation in banking. Methodologically, these essays share a focus on building theoretical models of closed and open economies to address policy-relevant questions in macroeconomics, drawing on additional ideas from related fields such as public economics and finance.