Grain legumes provide numerous nutritional, agronomic and environmental benefits and are at the core of the sustainability challenges of agricultural systems. Yet, grain legumes are hardly cultivated in Europe, not least because of strong agronomic constraints that reduce their yields and increase yield instability. Two PhD theses were performed to 1) assess the potential of intercropping cereals (wheat, triticale) with grain legumes (lentil and winter white lupin) to reduce the impacts of agronomic constraints on legume production; 2) better understand the functioning of these intercrops to improve their agronomic and economic performances. Intercropping legumes with a low density of cereal increased total grain yield in almost all tested situations compared to sole crops. The better global performance of intercrops was mainly due to a higher acquisition of light and nitrogen resources resulting from complementarities between species within the intercrops. Moreover, the presence of the cereal reduced weed biomass and lentil lodging. Intercropping legumes with cereals is thus a suitable agricultural practice to foster grain legume production in Europe.