In France the spectre of downward social mobility regularly makes the headlines. Whether it actually corresponds to reality or merely reflects a legitimate fear, according to the National Statistical Institute (INSEE) the sense of living less well than the previous generation was of concern to one French person in four in 2015. And amongst those most worried by these questions were those belonging to the so-called middle classes, who felt they were falling down the social ladder. How much truth is there in this impression? Is the middle class losing ground in France and, more generally, in the developed world? And what is the situation worldwide? What statistical data do we have on the subject? Drawing on recent OECD studies, Julien Damon offers a global-level analysis of the dynamics of the middle classes, showing that they are tending to contract in the developed countries but expand in the emerging nations. Most importantly, he emphasizes that being “middle class” doesn’t represent the same economic reality in all parts of the world. In a context of increased polarization in employment and a higher cost of living, the Western middle classes, for example, find themselves increasingly under strain and there are major social and political dangers in such a situation.