- A new mathematical model that describes segregation dynamics of two distinct populations in a city is presented. The model associates segregation with an instability of a spatially uniform mixed population state. Segregated states correspond to alternating domains of overrepresentation and underrepresentation of a given population. A second instability designates a transition to a stronger form of segregation involving enclaves of pure population. The model is used to study neighborhood change processes such as displacements of transition zones and tipping point phenomena. The main significance of the model lies in the conceptual framework it introduces by relating sociospatial phenomena to dynamical system and pattern formation theories.