ABSTRACT This paper examines the multiple tensions arising in an Australian university and public sector collaboration that aimed to investigate an obesity intervention. A key site of conflict with the external collaborators emerged when we, the researchers, focusing on the experiences of marginalized local people, presented research findings that were at odds with the dominant understanding of obesity that framed the public health intervention. From those with a range of roles in the public sector, we received claims of misrepresentation and requests to change or not publicly release certain research findings. Drawing on the ‘policy learning framework’ of Dunlop and Radaelli, we examine these epistemic conflicts and point to the Achilles’ heels of the ‘engagement and impact’ agenda. From the perspective of government, the inherent weakness stems from the lack of control in a partnership, and from the perspective of academics, it is the danger of undermining trust in universities and the knowledge academics produce, through the process of engaging with government and being party to research that is designed to shore up a position that government has already decided upon. This case study has implications for academic and government collaborators who may benefit from explicit planning about how to negotiate discord around the processes of learning that occur in and across research, policy, and practice.