Abstract: High housing costs and the unaffordability of housing are understood, to a large degree, as a function of an undersupply of housing at the national or regional level. Cost and affordability are especially a problem in high-demand cities and neighborhoods. If so, then increasing housing supply, especially in these high-demand areas, should alleviate housing cost pressures. In my talk, I will present results from a study that tests this hypothesis on neighborhoods in twenty-three US metropolitan areas. The results have implications to the types of neighborhoods we aim to develop and their effects on costs and affordability.