Community voices. Emerging phenomena, forms of organization and methods of debate - The paper highlights the possibilities and limits of grass roots action by committees and other forms of self-organisation of civil society at local level in situations of conflict due to the siting of infrastructure projects. It traces a profile of the forms of direct mobilisation which can be attributed, at international level, to two families of possible strategies: strongly institutionalised strategies on the one hand (the French Commission Nationale du Débat Public, the Tuscan Regional law which is based on it) and specially formulated strategies for specific decision-making processes for which the tradition of United States type consensus building is perhaps the most influential. The limits and possibilities of each of these families have only been partly studied and knowledge of them is only partial, while there seems to be less frequent pursuit today of forms of dialogue and interaction in which some officially accepted principles may be accompanied by a relative openness to the priorities of the issues to be dealt with, to the sources of technical and scientific knowledge to activate and to the actors to be involved. To move further in this direction of work would lead to the construction of paths specific to each project, with a greater degree of transparency and legitimation.