The objective of the study is to propose a relational approach of a collective organization in a Localized Agrifood System (LAS) to grasp collective action processes. The study was conducted in a producers’ association in two municipalities of the Campos de Cima da Serra region, in southern Brazil, where a mountain cheese, the Serrano cheese, is produced. We first conducted social network analyses (SNA) through sociometric interviews with producers’ members of the association, to understand how the different actors of the LAS as well as their relationship patterns frame collective action. Second, an analysis of territorial proximity, conducted through semi-structured interviews with members of the associations, was crossed with the SNA, to observe how the proximities shape social interactions and act as levers to generate collective action. The SNA showed first that networks were centralized, the extension agents having the central position. They are the drivers of collective action, but following a top-down approach. Second, the analysis revealed a lack of trust and reciprocity among producers leading to low level of cooperation. The president of the association played a key brokerage role, essential for the cohesion of the network. Finally, we showed that territorial proximities are instrumental in shaping social interactions in LAS: the less the actors are geographically isolated and the more they participate in cultural life, the more they interact in the association. Hence, territorial proximity appears promising for improving trust, cooperation relations and therefore collective action by increasing interactions among actors.