Alternative Food Organizations (AFOs) seek to establish more sustainable practices in the food system. However, they might hold different conceptualizations of sustainability. Hence, we miss an overview of AFOs' conceptualizations of sustainability that allows grasping their overall transformative potential. In this paper, we analyze a broad range of AFOs active in food production, distribution, and consumers' advocacy to examine to what extent they share a common understanding of sustainability. Our empirical analyses focus on the Swiss canton of Geneva, we build on organizational survey data and detailed coding of the discourses published on their websites. We find that the environmental dimension of sustainability is more prominent and that weak and strong conceptualizations of sustainability are equally present in AFOs' discourses. However, important differences appear between food producers and distributors. The former have a multidimensional and strong conceptualization of sustainability, while the latter focus on fewer dimensions and a weak conceptualization. In spite of these differences, AFOs interact within a small but heterogeneous network.