This article is based on the results of three field works carried out in France, Algeria and Cameroon. It analyzes how actions and measures undertaken to reverse the process of land degradation in arid and semi-arid areas and to limit urban pressure on land generate inequalities and social exclusion. Different disciplines and methods are used : an economic evaluation in Algeria, a socio-economic diagnosis in Cameroon and the analysis of social and agricultural practices underlying local land tenure in France. The presented results show that the effects of these projects and actions lead mainly to opposite results compared to the expected objectives, both in terms of tenure and social impacts.