Fannie Mae and Freddie Mac are charted by Congress as government-sponsored enterprises (GSEs) to provide liquidity in the mortgage market and promote homeownership for under-served groups and locations. They purchase mortgages, guarantee them, and package them in mortgage-backed securities (MBSs), which they either keep as investments or sell to institutional investors. This book examines Congressional interest in Fannie Mae and Freddie Mac which has increased in recent years, primarily because the federal government's continuing conservatorship of these GSEs, at a time of uncertainty in the housing, mortgage, and financial markets, has raised doubts about the future of the enterprises and the potential cost to the Treasury of guaranteeing the enterprises' debt. Since over 60% of households are homeowners, a large number of citizens could be affected by the future of GSEs.