In big French cities, because of a school catchment area policy based on the place of residence, there is a strong correlation between socio-residential segregation and school segregation. But the latter is not the exact and mechanical reflection of the former, because of many possibilities of avoiding the local public school. This chapter will present and discuss how and why school segregation is higher than residential segregation, and to some extent why school issues are more and more interwoven with residential strategies. First, we show that school segregation is the result of many processes related to school policies, parental strategies and urban inequalities. Then, we show that school segregation has not only an impact on school achievement, but also on more qualitative issues which deal with the perception of inequalities and the feeling of discrimination.