Growing a second crop in a year, either following an early summer harvest (double crop) or by sowing into the previous autumn-sown crop (relay crop), enables additional production, whether for feed, food or energy purposes. This practice of double cropping can generate additional income while providing support and regulation services. As such, it can be seen as an ecologically intensive form of agriculture, but also as an opportunity offered by climate change. The decision-making process leading to double cropping is based on a number of factors linked to soil and climatic conditions, but also to the expectation of gain and the perception of risk. The CASDAR project "3C2A: Three crops in two years" (2019-2023), which gathered 15 partners (farmers, advisors from chambers of agriculture, engineers from technical institutes, researchers), was set up to create useful references for double cropping in south-western France, encompassing the regions of Nouvelle-Aquitaine and Occitanie. The aim of this paper is to illustrate the potential interest of soybean and sunflower as second crops in south-western France by means of a qualitative analysis of farmers' perceptions of the risks and opportunities of this practice, enriched by a 4year on-farm assessment of the agronomic and economic performances of double cropping (130 fields) and at the experimental station, where a range of varieties were compared over a 3-year period. With the support of agronomic simulation (SPA 1 , STICS 2 ), it was possible to assess the robustness of the conclusions (feasibility, productivity) over longer climatic sequences, for unexperimented soils, climates and cropping practices, and for climate change scenarios. It was also possible to assess the environmental impacts (water requirements, drainage, nitrate leaching) of double crops in the South-West of France.