To face up to the multiplicity of global changes, a deep modification of agricultural systems is required. It is necessary to increase the resource use efficiency and the resilience of agroecosystems, faced with climate change, resource increased scarcity, the occurrence of biotic and abiotic stresses and economic changes. This search for efficiency and resilience calls for an ecological intensification via the valuation of ecosystem services, especially production and regulation services. Several syntheses emphasize the important role of legumes to provide these services, thanks to their biological fixation, to their effects on subsequent crops in the rotation, and to their nutritional interests for food and feed. If the diversity of species and their modes of integration into farming systems offers a wide range of products, and allows to suit local soil and climatic conditions, the disappearance of legumes in European farming systems raises question. Several studies highlight the insufficient knowledge by the stakeholders of their environmental impacts, but also insufficient economic valuation of these species in the agro-industrial system, locked in favor of the dominant species. As for other new crops, which development is made possible thanks to a combination of technical and organizational levers, routes for unlocking should be investigated by combining a shared knowledge of ecosystem services from legumes and an organization of stakeholders around new sectors and new outlets. This analysis must take into account the specificities of territories. The aim of the project is to study and build with stakeholders the conditions for a greater integration of legumes in farming systems, and to estimate the effects expected, from the perspective of a sustainable management of territories and resources. The heart of the work will be to design and evaluate, with local agricultural stakeholders including three cooperatives partners of the project and representing three regions, territorial scenarios of integration of legumes, economically viable. This project will be conducted as a participatory-action research. The design of scenarios of distribution of cropping systems in territories, adapted to the conditions of the study areas, will be based on a shared knowledge of agronomic performance and environmental impacts of a variety of legume species and on the socio-economic levers that could be mobilized at the farm and supply-chain levels to reintroduce legumes. This work will combine agronomic, economic and social approaches (through close collaborations between disciplines), and will address different scales (field, farm, territory and supply-chain). It will involve the stakeholders concerned by the agriculture changes in their territories. Its objectives are (1) an historical analysis of the reasons for the disappearance of legumes and the identification of routes to unlock the current socio-technical system at farm and supply-chain levels, (2) the acquisition and synthesis of knowledge on ecosystem services expected from legumes in the cropping systems of the studied areas, in order to mobilize these species in the design of territorial scenarios and new supply-chains, (3) the design and ex ante assessment of territorial scenarios of cropping systems including various legumes grown for different outlets and in different modes of insertion, and the identification of expected benefits for the territories in comparison with past cropping systems.