This paper reflects on ten years of transdisciplinary urban research by Mistra Urban Futures, a global centre focusing on the co-production of knowledge for more just and sustainable cities across the Global South and Global North. The paper focuses on one of the key challenges that Mistra Urban Futures has faced in its work: in addition to the competing interests and agendas of participants in co-production proces-ses, there are also often deeper underlying conflicting rationalities about many of the key concepts and substantive issues relating to making cities more just and sustainable, driven by ideological, educational, contextual and personal factors. These differences can be even more polarised between different cities and countries, including deep divisions regarding the fundamental nature of the problem, the ultimate goals and objectives of urban development interventions, and the key underlying concepts. This paper explores these challenges and reflects on the various approaches adopted by Mistra Urban Futures to facilitate the understanding of these differences and identify commonalities and overlaps of interest. Ultimately, understanding and engaging with the different rationalities of participants in co-production processes is essential for different actors to work together to co-produce and operationalise knowledge for cities that are more just and sustainable.