Assumptions about the role of neighbourhood effects are increasingly built into urban policies, particularly in relation to the role of spatial concentrations of disadvantage in perpetuating inequality and social exclusion. Nevertheless, hard evidence to underpin this assumption is still largely lacking. To help fill this gap, this paper focuses on the relationship between overall urban scale and the spatial scale of segregation, and on the implications of wider segregation for social outcomes at the individual level. Education is taken as a test case, because of the role of defined catchment areas in relation to school recruitment. Results show that: at given scales, larger city-regions are much more segregated; educational outcomes are only partly affected by neighbourhood effects for particular population characteristics; and greater individual inequality in more segregated areas is mainly due to positive impacts of segregation for more advantaged groups, rather than negative impacts for the most disadvantaged.