In the context of complex and unprecedented issues of global change, calls for new modes of knowledge production that are better equipped to address urgent challenges of global sustainability are increasingly frequent. This paper presents a case study of the new major research programme “Future Earth”, which aims to bring ‘research for global sustainability’ to the mainstream of global change research. A core principle of Future Earth is the co-production of knowledge with extra-scientific actors. In studying how the principle of co-production becomes institutionalised in the emerging structure of Future Earth, this paper points to the existence of three distinct rationales (logics) on the purpose and practice of co-production. Co-production is understood as a way to enhance scientific accountability to society (‘logic of accountability’), to ensure the implementation of scientific knowledge in society (‘logic of impact’), and to include the knowledge, perspectives and experiences of extra-scientific actors in scientific knowledge production (‘logic of humility’). This heterogeneous conception of knowledge co-production provides helpful ambiguity allowing actors with different perspectives on science and its role in society to engage in Future Earth. However, in the process of designing an institutional structure for Future Earth tensions between the different logics of co-production become apparent. This research shows how logics of accountability and impact are prominent in shaping the development of Future Earth. The paper concludes by pointing to an essential tension between being inclusive and transformative when it comes to institutionalising new modes of knowledge production in large research programmes.