Housing finance played a major role in the 2007-2009 financial crisis, and the housing sector continues to show considerable strains. The federal government's role in the single-family housing finance system has also grown substantially. As a result, policymakers and others have made proposals to change the system. To help policymakers assess various proposals and consider ways to make it more effective and efficient, this book describes market developments since 2000 that have led to changes in the federal government's role in the single-family housing finance system; analyzes whether and how these market developments have challenged the housing finance system; and presents an evaluation framework for assessing potential changes to the system.