Circa 2007 through 2009, the United States experienced a financial crisis, and a recession, that by many measures was the largest adverse economic event the U.S. has experienced since the Great Depression of the 1930s. Furthermore, these events had large negative repercussions on other economies around the world. The Great Financial Crisis and Great Recession were complex, and scholars will be arguing over important details of their causes and effects for decades to come. This paper reviews a number of contributing elements, focusing especially on two fundamentals of the twin "Greats:" excessive leverage, and excessive volatility in housing prices. The paper includes a package of 10 proposed reforms in real estate and financial markets that can mitigate the costs of future real estate-related downturns.