American neighborhoods have declined over the past few decades, contributing to rising isolation, mistrust, and polarization. Weaker social ties are leading to greater depression, anxiety, addiction, suicide, and alienation. Moreover, during the past 50 years, the number of high-poverty neighborhoods has tripled and the population of poor people in these neighborhoods has doubled, even as spending on welfare has soared. And yet, there are few systematic efforts to bolster neighborhoods. The role of institutions is key to reviving a neighborhood. The way these institutions structure—or fail to structure—relationships at the neighborhood and interneighborhood level affects the vitality of each locale and the well-being of everyone living there.