While a number of works question the alterity of alternative food chains, little has been said about the social processes under which new economic models are, or may be, developed within the broader movement around ‘short food supply chains’ (SFCs) in Europe. Considering SFCs as economic organisations, we propose an analytical framework based on New Economic Sociology and Convention Theory, enriched by Social and Solidarity Economics, to capture the social construction of new economic models in such chains. We apply this framework to two case studies: an open-air market promoting short food supply chains in France, and a partnership between an agricultural cooperative and several solidarity purchase groups (GAS) in Italy. Analysing the trajectories of the two initiatives, we highlight the processes through which new economic models are jointly built via interactions between different actors. Our results open two lines of discussion: one concerning the ‘new economic models' that emerge from the two cases, a second regarding the actors' participation in elaborating and enacting these new models.