Chicagoans have participated in block clubs for a century. Block clubs are small, geographically-based, voluntary organizations dedicated to improving the physical environment and regulating public behavior. Through extensive archival work in fragmented sources, this book reconstructs block clubs’ history. Block clubs are common in Chicago, the focus of this study, but have also appeared in many other American cities. Although the National Urban League, an African American organization, pioneered the form in black neighborhoods in the early twentieth century, after World War II Chicagoans of diverse racial and ethnic backgrounds readily joined block clubs across the city. These organizations conduct a variety of locally-directed activities, including cleaning up streets and alleys, transforming vacant lots into gardens and playgrounds, throwing parties, and preventing crime. Block clubs make it possible to trace the contours of urbanites’ relationships with local government and to discover how residents manage spaces that they do not legally control. Finally, this book concludes that “neighboring” should be considered a key analytical category of urban scholarship.