Grassroots social innovations are citizen-led initiatives that develop bottom-up solutions to societal challenges. Alternative food networks (AFNs) are innovations which propose alternative schemes for distribution and consumption of food—such as community-based agriculture or food cooperatives—which can improve the well-being of participants. Its potential for social work and social services has been recognised, but remains underexplored. This paper proposes a theoretical framework based on the capability approach in order to explore the impacts, drivers and factors at play in the expansion of well-being in participants in AFNs. This framework is applied to address seven cases of different kind of AFNs in Valencia (Spain) and to explore implications and strands of action so community social services can make use of AFNs. The study draws on information from thirteen interviews with participants of AFNs, local experts and policymakers; from secondary sources and from participant observation. It deductively uses the categories in the framework and inductively identifies specific capabilities, drivers and factors. The results show that AFNs expand well-being in several aspects of human experience. They are highly diverse, from more reformist to more radical, so they can mobilise different publics. Social services can benefit from this impact and diversity.