Rather than being considered as problems, one should understand environmental conflicts as expressions of the limited ability of spatial planning activities to take into account new expectations of the public. It is therefore a challenge to understand causes of environmental conflicts and suggest answers that would contribute to the renewal of the planner’s way of doing.The first part of this research intends to understand what environmental conflict really is and means. We indeed identify the main mechanisms of this conflict with a review of litterature on this theme and by our own analysis conducted on two environmental conflicts. We point out three levels of conflict :interpersonal, public and territorial conflicts. In order to address these mechanisms, we suggest toimplement “management principles” : intervention of a mediator (third party) within a negotiation solving approach open to all parties and closely linked on one hand to public participation and on the other hand to the decision making process.The second part consists of an assessment of implementation of these management principles. Because of the drawbacks of the so called US approach environmental mediation and the absence of such principles in France, we have analysed participatory/collaborative approaches based on intervention of a mediator in five countries (Germany, Belgium, the Netherlands, Switzerland and Quebec -Canada-). These observations let us confirm usefulness of the mediator intervention. Management of conflict is however possible only if this intervention is recognized at the same time by political and administrative decision makers and inhabitants. This political and administrative recognition however put into question the use of mediation as a new tool of public regulation. It boils down to saying this approach would reinforce power of those who are actually questioned through environmental conflicts. ; Plutôt que des dysfonctionnements, les conflits d’aménagement peuvent être appréhendés comme des signes de dysfonctionnements ...