This chapter discusses the theoretical framework supporting the idea that knowledge can be governed as a commons, i.e., as a resource used by a group of people who have self-developed a set of rules to manage the social dilemmas derived from its collective use. It discusses how the commons framework could also contribute to articulate the sharing of Traditional agricultural knowledge (TAK) at different scales. The chapter focuses on landrace knowledge held by gardeners of Vall Fosca, a rural Pyrenean valley of Northeastern Spain, and managed through an informal social network of seeds exchange promoting cultural identity and social cohesion within the community and likely enhancing agrobiodiversity conservation. The chapter concludes by exploring the degree to which a commons-based governance can be considered a contestation to commodification and enclosure movements that threaten the maintenance of TAK systems, and thus people’s ability to sustain environmentally and culturally adapted food systems.