In this research project, I develop a "diagnosis of the present" (Foucault) about the field of urban design in France. Starting from the observation that current professional project practices in urban design remain difficult to understand and blurry - in spite of having been analysed by researchers for several decades -, I consider the hypothesis that this may be a result of the way researchers regard them, rather than an enigmatic dimension of professional project practices themselves. Relying on Foucault's "archeology of knowledge", I then conduct an analysis of a corpus of recent research in urban design. It shows that researchers overwhelmingly take professional practices as on object of sociological enquiry, adopting a reflexive stance towards them. Using the concept of "reflexive modernity (Giddens, Beck), I then wonder whether urban design project practices in France might be a typical case of reflexive modernity. Soon, I notice a contradiction : "reflexivity" has been much conceptualised in urban design research since the end of the 1990s but it seems that the most critical aspects of "reflexive modernity" theories have been avoided. Instead, reflexivity in every shape and form is legitimised and encouraged. Practitioners should be reflexive, researchers can bring them more reflexivity, new forms of reflexive cooperation thrive... How can such a reversal of the concept of "reflexive modernity" be explained ? In the last part of this research, I dig out the "genealogical" origins (Foucault) of the notion of "reflexivity" in urban design in France. The appearance of this concept in research in the late 1990s seems to serve mostly as a justification and catalyst of reflexive practices that had been existing for years. It is possible to trace them back to the late 1950s, when the French State developed a "concern for itself" (Bezès). In those days, a discursive nexus springs up, that connects urban planning practices, the need for institutional reflexivity and a new conceptualisation of "change". Nowadays, this nexus still exists, though it evolved after several decades of economic and social transformations as well as the development of "project" practices in urban planning and design, and the restructuring of the French State's governing practices towards what some have named "distance gouvernment"(Epstein). Reflexivity has become almost compulsory for professionals, penetrating to the heart of their everyday work and prompting permanent changes, to the point that those practices have become ungraspable. Do these changes have any other objective than change itself ?