There is a growing awareness that transition towards more sustainable agriculture requires a new knowledge base in terms of both new content of knowledge and new processes of learning. Such a knowledge base should go beyond standardized science-driven solutions and integrate other knowledge sources – including farmers themselves – and learning modes. Within the EU-funded transdisciplinary RETHINK project, we dig into farmers' knowledge and learning practices in relation to constructing sustainable agriculture and strengthening agricultural resilience. Local farmer knowledge and informal learning practices turned out to be among the key knowledge sources farmers rely upon. This knowledge appeared critical for enhancing agricultural sustainability and resilience. Why is this? Read more in What farmers know and Optimising this knowledge and Local and farmers' knowledge matters! How integrating informal and formal knowledge enhances sustainable and resilient agriculture.