This is another piece written on Serge Michaïlof’s request for “A quoi sert d’aider le Sud?” He asked me to problematize the urban question as an introduction to the part of the book relating to cities and infrastructures. These types of synthesizing exercises in a compact format are difficult. The text reflects the concerns at that time of urban professionals regarding the magnitude of the stakes and the international community’s underestimation of them. The latter had not fully recognized the phenomenon of world urbanization, which was revolutionizing the paradigms of development economy.