The need to reduce urban sprawl and increase density in U.S. cities has become a central issue in urban planning as cities seek to decrease automobile dependence, reduce emissions, and confront the problem of global warming. Since urban sprawl is seen as a major contributor to global warming, there is a growing realization that the American dream of a single-family house on its own lot in a suburban context is not sustainable in the long term. Essentially, this means finding ways to accept and welcome density. For development in existing neighborhoods (infill), the problem is that higher-density developments are seen as a threat to single-family homes and property values. Design, therefore, becomes a critical factor – good design for infill housing that increases density embeds the infill within a larger context. Design takes on the expanded goal of ensuring that it is possible to envision each project or development in relation to broader societal goals and positive ideals. Design for increased density is critical for residents to be able to visualize the trade-offs involved, to see how density is not always about detracting, but actually helps create better public spaces, retain essential services, sustain a walkable environment, and potentially, keep housing more affordable. This paper reviews the role of urban design in the global warming equation – i.e., how good design becomes essential to the goal of reducing urban sprawl and building cities more compactly.