This chapter develops a multi-level conceptual model of segregation, by using three conceptual levels – individuals and households, generations, and urban regions. Different socio-economic groups sort into different types of neighbourhoods and other domains, leading to patterns of segregation at the urban regional level. At the same time exposure to different socio-economic contexts also affects individual outcomes, and this subsequently leads to sorting processes into neighbourhoods and other domains. This vicious circle of sorting and contextual effects continuously crosses the three levels, and leads to higher levels of segregation. The chapter concludes with a discussion of several intervention strategies that focus on breaking the vicious circles to improve cities as places of opportunities by investing in people, in places and in transport.