On the French island La Réunion and in a French legal context, where emphasis lies more on 'land regulation' than on 'land security', an experiment combining research and development is undertaken, with the objective of coordinating political good-will and land control. This article deals with the pilot scheme of 'citizen land mediation' MEDIAC, which introduces the problems of 'land security' in conjunction with land regulation. In the commune of Cilaos, a tourist area where agriculture remains important for sustainable development, farmers are confronted with an unquestionable lack of land security. The latter is increased by phenomena such as speculation, erroneous character of the land registers, joint possession and a general attitude of mistrust towards the administration. The various institutions encounter many difficulties in implementing their tools for land regulation. Nevertheless confronted with the need to preserve agriculture those involved in land control support the idea of land mediation. Land mediation, with its social and territorial approach, which is necessary to mitigate land constraint, constitutes a step towards the creation or the renewal of' bonds between the various actors, private and institutional. It authorizes the actors to engage in a common reflection on the management of 'their' space, as experienced on a daily basis. The term 'citizen', which characterizes 'land 'mediation', points to the need for a participative strategy associated with an evaluation of environmental or land problems in order to transpose the principles and criteria of viable and sustainable development into the project planning of development or space management by integrating social concerns. The mediation process makes it possible to bring together the multiple perceptions and objectives of the various actors. It highlights the links between individual interests and more collective dimensions. The introduction of land mediation in Ilet à Cordes requires the ide