This paper explores the articulation between gentrification and social class, in the context of the debate that opposes the notions of replacement and displacement of the working class. Working from Marxist sociological analyses of the professional-managerial class, this social geography study reviews statistical data spanning over three decades to demonstrate the magnitude of gentrification in Paris, both on the scale of the city and on that of its metropolitan area. The author examines detailed socio-economic categories from French population censuses and focuses on the household population rather than on the sole working population, from the early 1980s onward: through this methodology, the author intends to prove that, contrary to Préteceille’s assessment, gentrification is indeed the main factor of socio-spatial transformation in inner Paris and contributes to the diverse forms of social upgrading that affect the metropolitan area as a whole. This process has brought about a shift in the scale of segregation, which has increasingly acquired a micro-local dimension.