The sustainability movement in the United States has increasingly embraced the environmental benefits of dense, mixed-use walkable communities. However, it has been slower to codify these benefits into formal project review and rating systems for investment. Sustainability advocates have historically focused on building-level performance, with a particular emphasis on energy, water, and waste management. This emphasis on the building as a stand-alone structure, separate from its neighborhood context, reflects both the challenges of neighborhood-scale data gathering and the fragmented nature of neighborhood development in the United States. As a result, individual projects may be high-performing in some respects without actually addressing the larger issues of site and neighborhood design that are so vital to sustainable communities. Fortunately, public policymakers and private industry leaders have recently begun to develop a more robust set of tools for measuring sustainability at the neighborhood scale.