Complex political decisions increasingly require scientific knowledge and expertise. But the exchange between actors from the political and the scientific systems is confronted by challenges. Science policy interfaces are needed in order to overcome the barriers to communication. This article analyses and discusses the importance of foundations as science policy interfaces. To this end, we will first present the salient features and functions of foundations as organisations in the framework of theoretical considerations and discuss their fundamental suitability as mediators of scientific knowledge in the political process. We will then identify the significance of foundations as science policy interfaces using a quantitative content analysis of references to foundations in the debates of the 18th German Bundestag.