This paper investigates the European Technology Platforms (ETPs) in wind power and in CO2 capture and storage supported by the European Commission (EC). It examines the role of these Platforms in shaping the trajectory of European energy technology policy, and shows that the EC’s support for the ETPs marks a change from a solely evidence-based policy approach to the use of bottom-up policies designed to mobilize human capital based on social actors’ expectations, uncertainties and visions. These two ETPs include hitherto missing ‘key players’ who can enhance commercial legitimacy on both the input and output sides of the system. This constitutes an important, though narrow, type of legitimacy in regard to specific technology developments, and questions remain about the performance of the ETPs in relation to small and medium-sized enterprises and social representation. This paper provides a valuable first qualitative analysis of this phenomenon which is emerging as a new policy instrument.