Participatory processes of agroecological transitions at territorial scales are becoming a widespread practice. However, systematic research based on empirical processes remains scarce. In this paper, we systematize the experiences of five cases of co-design for agroecological transitions in Spain, in different territorial contexts and scales, applying the framework of Local Agroecological Dynamization. The systematization has involved professional facilitators of each project and is based on the primary and secondary data they provided. The systematization describes a sequence of milestones to walk through to implement transformative, participatory processes of transitions and suggests some principles for the design of such processes. The paper highlights two elements that define the transformative character of the cases: the activation of social creativity based on the material and relational features of the territory, and the strengthening of local socio-economic actors in the framework of a plural social subject to promote the transition. More empirical, action-oriented research is needed, in different territorial contexts and long-term processes, to deepen the understanding of such issues.