International audience"Living together" is becoming a central issue in the production and management of sustainable cities. After having overcome technical constraints, sustainable cities would face limits due to the common practices of their inhabitants. The "living together" watchword, widely used in eco-district operations, is presented as a mean to transform the way people live in such neighbourhoods. Built on the observation of the construction of eco-district assessment indicators, the present article highlights the debates and paradoxes in the making of the « living together ». The analysed debates show that eco-district inhabiting assessment is the product of the tension between:-an a priori definition, based on a "living together" ...