Market theory positions the consumer as a rational choice actor, making informed schooling choices on the basis of "hard" evidence of relative school effectiveness. Yet there are concerns that parents simply choose schools based on socio-demographic characteristics, thus leading to greater social segregation and undercutting the potential of choice to drive quality improvements. In this paper, we explore segregation by examining catchment areas for a range of public high schools in a specific middle-class urban area. We focus on socio-demographic characteristics, including levels of income, country of birth and religion affiliation, in order to explore residential segregation according to public high school catchment areas. Our data suggest distinct residential segregation between catchment areas for each public school within our data-set, particularly for the schools deemed to be popular and rejected, that may pose risks for broader equity concerns. We argue that, in contrast to market theory, even more affluent and active choosers are not equipped with information on the programmatic quality of their different school options, but instead may be relying on socio-demographic characteristics of schools--through surrogate information about the urban spaces that the schools occupy--in order to choose peer groups, if not programmes, for their children.