Rowan's essay traces the emergence of a new ecological discourse that began to shape thinking about urban life across disciplines in the mid-twentieth century. In the 1950s, urban institutions such as the New Yorker embraced what historians Michael Barbour, Robert McIntosh, and Gregg Mitman describe as “community” ecology. Later, postwar urbanists such as Jane Jacobs would draw on the authority of community ecology to reckon with the physical and social transformations then being carried out within New York City's urban renewal programs. Offering scientific evidence of cooperation as a fundamental biological principle and defining diversity as a critical element of communal stability, community ecology helped city observers challenge the logic of urban renewal by infusing public relationships that had previously been dismissed as emotionally bankrupt with new affective value. Attending more carefully to how these urban ecologists redeveloped the ways in which their communities should be understood, Rowan argues, allows us to reexamine the legacies left by those who opposed it—a heritage that many now fear turned a blind eye to issues of social justice.