Talen and Koschinsky demonstrate that Chicago's walkable, dense, mixed-use neighborhoods score poorly on measures of health, accessibility, safety, and social interaction. This comment raises and discusses several questions: How good a frame is ``sustainable'' for describing the urban form the authors measure? What are the connections between ``sustainable urban form'' (SUF) and good outcomes for
... [Show full abstract] assisted tenants in Chicago? Do SUF neighborhoods provide better conditions for assisted housing tenants? How does the scale at which we investigate this question influence the answer? More broadly, how do we expect SUF to work for assisted housing tenants and other low-income people? Finally, to what extent is SUF a necessary and sufficient condition for ensuring long-term income diversity through investment in affordable housing? The answers to all these questions are still open, making this is a promising time for more fine grained research supporting efforts to bring greater social justice to the city.