Housing is a key component of the U.S. economy: in 2001, housing comprised more than a third of the  nation’s tangible assets, and, in the form of home building and remodeling, housing consumption and  related spending represented more than 21 percent of the U.S. gross domestic product. Since 2001,  home sales, prices, equity and debt have all grown substantially, enabling millions of Americans to  purchase ever-greater amounts of goods and services (Joint Center for Housing Studies 2006). Housing that is decent-quality and affordable (generally defined as consuming less than 30% of a family’s income) enables families to better enjoy a variety of life outcomes, such as family stability, good health, employment, education and recreation. Decent and affordable housing also contributes to the improved physical, economic, environmental and social health—the sustainability—of communities (Millennial Housing Commission 2002). These impacts are especially important for lower- income households and other underserved populations. Despite the general strength of the U.S. housing market, the benefits of housing, and of stable, vibrant communities, are unequally distributed. Examples of these inequalities include: residential segregation, gaps in homeownership rates by race, sprawl-type development patterns and shortages in affordable housing. Most recently, in the wake of Hurricane Katrina, the challenges of securing basic shelter and rebuilding homes and communities have fallen disproportionately on minority and low-income populations.