The OECD has a strong legacy in shaping innovation policy mixes. The purpose of this paper is therefore to provide a better understanding of how the OECD is currently shaping new policy mixes for sustainability transitions. It provides a detailed account of the uptake of system innovation thinking, a key concept in transition studies, at the OECD. It takes an ethnographic approach combining desk research with participant observation, allowing to study ‘discourse in the making’. The paper traces the different translation and inscription strategies pursued. It finds that despite purposeful efforts, system innovation has not been institutionalised in the core activities of the organisation, thus can be considered ‘lost in translation’. It concludes that legacy effects created a number of sticking points that can be categorised under three main categories: (1) institutional, arising from previous ways of working; (2) cognitive, arising from ways of framing and knowing and (3) political, arising from pre-existing power relations. Suggestions are made for both innovation policy academics and practitioners interested in promoting a transformative innovation agenda.