Rosanvallon (2008) recently stated that democracy as a political regime is becoming more and more complicated. Since the end of the 1980s, national governments in Europe have settled more and more participatory and deliberative institutional-settings. The “deliberative imperative” (Blondiaux, Sintomer, 2002) is now developing a new frame: we need to create new institutions to be able to discuss and deliberate before we take any decisions for the common good. From a case study about a French participatory process, called “Grenelle de l’environnement”, which was supposed to facilitate deliberation between NGO’s, state, local authorities, and trade unions, thus forging political consensus through dialogue, devising and implementing public policies fostering sustainable development. We will argue in this paper that when people are experimenting participatory designs, they show more concern and awareness of socio environmental risks. They are more creative. Still those democratic arenas need to fulfil some characteristics to reach collective problem solving and to be taken into account by our representatives. Fung (2010) recently demonstrated that elements of deliberative quality include mutual respect, understanding, pro?ering of reasons and arguments, equal opportunity for discursive engagement, and neutrality. We will study whether these characteristics are efficient during two “Grenelle de l’environnement” working group deliberations from 2007 to 2008. We will focus our analysis on the way NGO’s really take part in the grenelle process : who contribute, do their propositions matter, do they claim for legitimacy for instance. This case study relies on an exhaustive meetings data and archives analysis, completed by participants’ interviews. These research results are part of a project financed by the French research agency (ANR) called “Parthage”.