This paper reflects on ten years of transdisciplinary urban research by Mistra Urban Futures. Mistra Urban Futures was established in 2010 as a global centre focusing on the co-production of knowledge for more just and sustainable cities. The core partners in Mistra Urban Futures are from four countries (Sweden, the United Kingdom, Kenya and South Africa), and the centre also works in two other countries (India and Argentina). In addition to undertaking local knowledge co-production work in each partner city, Mistra Urban Futures has also linked up local work into international transdisciplinary projects. 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 processes, there are also often deeper underlying conflicting (or diverging) rationalities about urban development. Many of the key concepts and substantive issues relating to making cities more just and sustainable are highly contested. Within cities, people and organisations from different sectors and different disciplines often have very different understandings of what the problems and solutions are, driven by ideological, educational, contextual and personal factors. These differences can be even more polarised between different cities and countries, for example between cities in the global North and global South and between cities in countries with different political cultures. For example, there can be deep divisions about the fundamental nature of the problem (poverty, inequity, lack of economic growth, lack of political empowerment, unsustainability, lack of government capacity, etc.) and the ultimate goals and objectives of urban development interventions (such as equity, economic growth, maintaining the status quo or radical change). In addition, concepts such as such as “fairness”, “justice” and “resilience”, and substantive issues such as “public transport”, “sustainable urban food systems” and “tackling climate change”, can mean very different things to different people and in different places. 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. For example, most of the Mistra Urban Futures projects had initial phases to identify and understand the different views of participants in order to be able to identify common ground for collaboration. In some cases, the different terminologies and concepts used by people from different sectors or disciplines required developing a common conceptual vocabulary during this initial phase. In one particular project in Cape Town, the research method included the mapping of the different rationalities of key stakeholders as a basis for identifying opportunities for further collaboration. Having a diversity of rationalities and approaches often stimulates creativity, resulting in the development of innovative methodologies, policies and practices. Ultimately, understanding and engaging with the different rationalities of participants in co-production processes is essential for different actors to successfully work together to co-produce and operationalise knowledge for more just and sustainable cities.