This invited conference was intended at offering a sociological perspective on agroecological transitions at the scale of food systems. It shows the need to combine a socio-historical analysis of lock-in mechanisms and a comprehensive analysis of change mechanisms at both scales of farmers and agrifood systems. It develops a territorial approach to agrifood systems agroecological transitions. Addressing transitions requires a systemic but also a critical perspective, looking at controversies and power reconfigurations. The conference is concluded with an insight on the combination of localised approaches and larger translocal exchange networks bringing together academic and practicioners.