The promotion of biofuels has caused more societal controversies and tension than almost any other environmental topic has in recent years. Presently, the approach of the European Commission is to avoid the worst socioecological risks by simultaneously implementing sustainability criteria and maintaining promotional policies for biofuels. But how was this ‘sustainability approach’ in bio-fuels policy developed and which actors influenced its development? How big of a role did scientific findings play within the political process as compared to lobbying? Did scientists fail to indicate relevant sustainability problems early enough? If not, was it the European Commission or European politicians that did not heed the early warnings? Finally, the important question arises: did impact assessments (one of the main instruments used by the European Commission to examine the effects of policy proposals on society and the environment) fail within the context of biofuels? This article tries to give at least some answers to those questions.