If low-income families can’t afford the suburbs and the cities, where should they go? For the first time in American history, it makes sense to talk about whole regions of the country “gentrifying”—whole metropolitan areas whose high housing costs have rendered them inhospitable to low-income families, who, along with solidly middle class families, also feeling the crunch, have been paying higher housing costs or migrating to low-housing cost (and low-wage) areas like Texas, Arizona, or North Carolina. Underlying both of these phenomena—high housing costs in the suburbs and high housing costs in the cities—is a relatively straightforward problem of supply and demand. A city’s ability to remain affordable depends most crucially on its ability to expand housing supply in the face of increased demand. Among the people who care most about high housing costs there is a lack of understanding of the main causes and the policy approaches that can address them. The central message of this Article is that the housing advocacy community—from the shoe-leather organizer to the academic theoretician—needs to abandon its reflexively anti-development sentiments and embrace an agenda that accepts and advocates for increased housing development of all types as a way to blunt rising housing costs in the country’s most expensive markets.