Supporting farmers in the context of agroecological transitions is a challenge for the agricultural extension services and training. In order to contribute to support such services in facing this issue, we built a conceptual framework that allowed us to analyse how farmers' activity is transformed by agroecological transition. We then propose recommendations for services oriented towards the support of such transitions. More precisely, we highlighted five main principles of farmers' activity during an agroecological transition: the progressivity of change, the singularity of the knowledge involved, observation and experimentation, the reconfiguration of "values" and cooperation and participation in peer groups. Based on the theory of inquiry of John Dewey, we propose a conceptual framework that makes it possible to grasp all these principles together to analyse farmers' activity during their agroecological transition in a systemic way. We then highlight the need for new advisory skills so that advisors can induce and support farmers' inquiry.