Not only whether biofuels should be politically promoted at all, but also through which policy instrument this should be done has been a matter in dispute in German biofuels policy. In this context, the tax exemption for biofuels has been abolished in favor of a mandatory quota in 2006. This paper analyzes the political struggle over biofuel policy instrumentation in Germany, especially focusing on the way how a mandatory quota has been discursively framed over the years as being the better instrument. The results show that it is ultimately not a question of the factual properties of a policy instrument, but rather of the social construction of such an instrument and the attribution of meaning to it whether it is promoted by or prevails because of its market-based arguments.