The Millennium Development Goals – proclaimed in the year 2000 and aimed at guiding the planet’s management and its priorities for the next fifteen years – were widely based on the concept of “sustainable development”. This concept will be once again broadly discussed in 2012 on the occasion of the United Nations Rio+20 Summit. It will be an opportunity to decipher to what extent the city, as much from a spatial as from a societal point of view, is a stakeholder in such debate. After analysing the various interpretations of the concept of “sustainable development”, this article questions its implementation within the framework of the MDGs, and the role assigned to urban actions. Due to its complexity and in spite of its economic and demographic prevalence, urbanism has been by-passed by a number of international global initiatives launched to date. A series of options have been proposed to finally give the city the high profile it deserves in any sustainable development analysis, aiming as much at urbanistic and material production as at the social and economic balance of its inhabitants.