This paper looks at two districts of “planned social mixing” –new housing projects built in dense urban areas where a set percentage of apartments is earmarked for social housing. After discussing the ideological, socioeconomic and historical reasons behind these projects’ construction, the article goes on to show that their social composition is almost perfectly representative of the overall population of the greater Paris area. This has been achieved by attracting middle and upper class families to settle in the former working-class. An analysis of the residential choices of the districts’ inhabitants reveals that the owners are at the beginning of their real-estate careers and that the social housing renters tend to be relatively well off. This difference entails a disparity in age structures: 10 to 24-year-olds are much more numerous in the social housing households than in any of the other housing categories. Despite the ideals associated with social mixing, the analysis of the inhabitants’ social networks reveals weak social ties between inhabitants, largely structured by occupancy status. Nevertheless, these neighborhoods do manifest socializing effects namely on middle and upper class inhabitant’ representations of working classes and of their own position in the social space.