Planning in modem urban environments requires skills to address complexity in order to move towards sustainability. Co-production of knowledge in transdisciplinary groups represents a useful tool in such contexts. Using the concepts of epistemic communities, linguistic diversity and culture, the article proposes a conceptual framework for analysing complexity of co-production settings, as an indispensable means of managing complex challenges, thus making these complexities visible for the project leader (facilitator) and the participants of the co-production process. We evaluate the framework on the basis of inclusivity, cross-sectoral understanding, applicability in different contexts and time perspectives. Based on the framework, we identify several aspects that a process leader (facilitator) would need to address when preparing for a coproduction process: linguistic equality between participants, disciplinary integrity, a working culture of mutual respect, simultaneous mitigation and informed facilitation. Finally, the article suggests possible future research areas related to development of the framework, including (i) identification of levels of complexity and mapping specific tools to address complexity at each level; (ii) integration of other factors of complexity, such as political and institutional contexts, as well as diversity of gender and age in the facilitated group.