This paper analyzes the role of public action in the development of local food solidarity initiatives. It is based on the case study of a social grocery store located in a small town in Hérault, France. At first, the project was conceived by the Department as an element of its social policies. The main goal was to set up a social grocery store in a rural area without any food bank accessible, in a spatial justice perspective. To settle this top-down initiative, the Department relied on a non-profit organization that was already active locally and had a strong mobilizing power. Nevertheless, the local appropriation of the initiative was limited by an opposition movement led by food retailers afraid of economic competition, in a deprived small town. In this conflictual context, local governments first chose not to support the initiative. However, cooperation at the communal and intercommunal levels has gradually developed as a result of local political and institutional changes, and of the success of the initiative. Public action takes different forms depending on the institutional level. On the one hand, local actors mainly support the initiative through occasional actions, whose main objective is to provide a short-term response to a social need. On the other hand, at the Department and Pays levels, public actors aim at accompanying the initiative over the long term. They consider the social grocery store as an living lab to facilitate a systemic change in food systems and in social action. This reinforcement of public intervention is a driver for scaling the initiative and increasing its transformative impact.