This chapter focuses on urban building and housing interventions that have been evaluated at some of the highest levels of scientific evidence. Building and housing interventions strongly appeal to policy makers and the public who intrinsically recognize the basic human need for shelter. The most blighted and neglected human dwellings in cities provide a strong basis for motivating action. After all, one can clearly see a significant change in an area when old buildings and physical structures are razed and new ones constructed. Questions arise, however, in terms of the actual need for complete replacement with new structures, as opposed to more widespread renovations and preservation of old buildings. It is equally important to consider the effect that urban-revitalization activities—especially in residential districts—have on gentrification and the possible reduction of a city's affordable housing stock, which itself influences health and safety. The chapter then discusses examples of building interventions that have failed to produce positive evidence and ones that have shown success without causing significant dislocation or displacement.