In a national context of repeated lawful injunctions to increase the inhabitant-citizen participation in the public action, and a local context of break with the previous forms of governorship, the Paris Mayor Office organised from 2002 to 2010 an ambitious « concertation» around the urban redevelopment project of the central district Les Halles. This research is dedicated to the analysis of the setting-up conditions of a participative approach in the specific framework of a great urban planning project. The aim is to demonstrate the link between the project process and the participative process. Elements of method and analysis concerning the consideration of the inhabitant-citizen in the project are exposed. For this purpose, the various methods and temporalities of the project's approach and participative devices are precisely studied, using definitions of participation levels and standards of the participation and deliberation process. Assuming that it is pretty difficult to qualify evenly the intensity level of the citizen implication concerning an urban project studied in its duration, the analysis obviously shows that on the whole, the devices called « concertation» by the Mayor Office did not really impact the negotiation of the project in its main principles. In fact, the participative process remained most of the time confined to an advisory level (consultation). The position of the actors in charge of the urban project and their representations of the inhabitant-citizen status in the project process are a major explanation for the limited impact of the « concertation» in the project itself, but also in its attempt to appeal to the concerned public. However, obstacles to public action democratization in urban planning also result from the way the projects are conceived and realized. Nevertheless, the urban redevelopment of the district Les Halles has launched changes, even innovations in the City. Studying the participative process as an experiment allows to show its effects on the people involved, especially in terms of learning processes, as well as the possible evolutions, in the Parisian local context, of participative practices in urban planning
