A recent article [Vinkovic D, Kirman A (2006) Proc Natl Acad Sci USA 103: [19261][19262][19263][19264][19265] showing that the Schelling model has a physical analogue extends our understanding of the model. However, prior research has already outlined a mathematical basis for the Schelling model and simulations based on it have already enhanced our understanding of the social dynamics that underlie the model, something that the physical analogue does not address. Research in social science has provided a formal basis for the segregative outcomes resulting from the residential selection process and simulations have replicated relevant spatial outcomes under different specifications of the residential dynamics. New and increasingly detailed survey data on preferences demonstrates the embeddedness of the Schelling selection process in the social behaviors of choosing alternative residential compositions. It also demonstrates that, in the multicultural context, seemingly mild preferences for living with similar neighbors carry the potential to be strong determinants for own race selectivity and residential segregation.preferences ͉ simulation ͉ ethnicity ͉ integration ͉ neighborhoods A recent article outlined a model that can explain the way in which separation or segregation (clustering) can arise in physical processes and is thus a parallel to the clustering outcomes of the Schelling segregation model (1). The physical analogue is interesting and it is intriguing to learn that there are physical parallels to social processes with specific commonalities in the physical processes of clustering and the social process of residential separation and segregation. That said, it is not completely clear that we have advanced our understanding of segregation and segregation dynamics by generating a physical analogue to the Schelling model. Although the physical analogue explains clustering and separating, the most important issue in the Schelling model, from a social perspective, is how choices play out in the social fabric and lead to segregated residential patterns. We show here that there are well articulated mathematical explanations for social segregation, that simulation studies with relatively simple utility structures can replicate complex and sometimes subtle segregation patterns seen in real urban environments, and that data from surveys of preferences reiterate the role of social distance in segregation outcomes.The original Schelling agent model was disarmingly simple in its construction (2, 3). It posited that an agent, a model representation of a household that could be white or black, preferred to be on a square on a checkerboard in which half or more of the eight adjacent neighbors were of a similar color. In the economic context, this was seen as having utility one compared with having utility zero. Schelling used simple simulations based on such hypothetical preference schedules to show that the adjustments of individual households responding to changes in composition on the checkerboard invariably lead to ...