In this contribution, two case studies of action research illustrate different kinds of partnerships. One kind gathers partners within education, teachers of various school subjects and school levels working together with the researcher on didactic ‘thinking tools’ that empower teachers to plan and implement a transformative and action-oriented ESD. The other gathers pedagogical experts, field specialists and teachers to co-create, with the researcher, a lesson plan on rivers planning combining geography and ESD. The diversity in the first partnership lies in the various school subjects and levels, including an interdisciplinary aspect and the idea of a curricular progression, whereas the diversity in the second partnership lies in the very different nature of the involved partners, including a transdisciplinary knowledge construction. In this contribution, we will firstly identify the roles of the different partners in the action research process, with a special focus on the researchers. Secondly, we will analyse the opportunities and challenges that arise from these partnerships in order to improve possible synergies while implementing an ESD that enables societal transformation towards sustainability.