This contribution analyses the difficulties of biodiversity policy-making and the role of science. It addresses biodiversity scientists' struggles to communicate the value of biodiversity to policy-makers, and the tensions between producing policyrelevant research and being perceived as too prescriptive. The author argues that it is important for biodiversity scientists to acknowledge and engage with the political aspects of biodiversity policies. A first step is to recognize the diversity of valuations and preferences among various stakeholders of different trade-offs, and the power relations between the stakeholders. A transparent presentation of a broad range of policy options, including an explic it description of the assumptions and models underpinning them, is a further requisite. Such presentations in turn require better understanding of the way institutions governing ecosystem (services) emerge and are established.