The EU Strategic Energy Technology Plan (SET-Plan) was adopted in 2008 to steer the funding of low-carbon technology research and innovation in Europe and thus accelerate the development and deployment of such technologies. Examining how and why the Plan attained its objectives, we first find that research and innovation funding came to steer the development of the SET-Plan rather than the converse. Second, we find three main explanations, drawing on theories of EU integration and policymaking: 1) differing research and innovation priorities among state, non-state (industry and research community), and institutional actors within the EU, making the Plan contested and leading to the mobilization of actors whose priorities had not been included in the Plan; 2) weak EU-level authority to govern the Plan; 3) diverging alignment between the Plan, constituting EU’s low-carbon technology push policy, and EU market pull policies, such as carbon pricing. These observations have relevance to other international efforts, such as Mission Innovation linked to the Paris Agreement.