The intensive use of natural resources in the Maghreb, in particular by the agricultural sector, is creating an urgent need to design governance mechanisms at both the local and national level. Groundwater has become one of the most fragile of these resources. The rapid development of groundwater use for irrigation in the Maghreb has resulted in significant agricultural growth, but in many regions, such development has become unsustainable because of aquifer overexploitation or water and soil salinization. Adequate instruments to address this unsustainable use are not easy to design and implement, for there are many informal groundwater withdrawals by farmers, and water resource management organizations have limited intervention capacity. The paper examines groundwater use and management in Morocco, Algeria and Tunisia based on a study of national institutional and policy mechanisms and nine local case studies. Overexploitation creates environmental, economic and social risks, and there are already significant identifiable impacts in several of the case studies. Farmers address the problem of decreasing borehole flow-rates (or water salinization) either by constantly investing more in order to continue to have sufficient quantities of fresh water for their crops, or by adjusting their cropping systems to adapt to this decrease. In the absence of specific policies, there are increasing differences between those farms that have the resources to continue investing more in order to have sufficient water, and those that have to adapt their crops to the shortage. Legal frameworks have laid management foundations, but they only have a limited impact, in particular, because of the generally informal nature of such uses. Different strategies are currently being discussed at national level, and are often focused on contractual approaches with the farmers. Concomitantly, some collective initiatives have been conceived at local level. The range of policies implemented to address this unsustainable use is very broad-based, and entails both increased water resources and the adoption of instruments to limit increases in withdrawals. These instruments are based on control and incentive mechanisms. In the cases considered, jointly used instruments have made it possible to limit increases in withdrawals and to facilitate water enhancement, without, however, restoring the resource-use balance. The design and implementation of strategies for sustainable aquifer exploitation require the building of coalitions of actors, which should include organizations responsible for water resources, those involved in agriculture, but also - and especially - farmers. Support could be provided to the formation of such coalitions and to their reflections on possible options to assist an agricultural economy based on sustainable aquifer use.