In recent decades, scientific knowledge has been extremely important in informing environmental decision-making processes on e.g. air and water quality, and coastal zone management. However, in many cases the relationship between science and policy is often still troubled and contested. This can be attributed to the complex and multi-layered character of the field of environmental governance, and the involvement of a broad array of stakeholders with conflicting stakes and needs. Issues include the selective use of knowledge, knowledge being ignored by policy-makers, the use of counter-expertise, and differences in the demand for and supply of knowledge in terms of language, timeframes, and level of detail. Consequently, opportunities to enrich decision-making processes – i.e. the use of knowledge to gain a clearer picture of the problem setting, underpin and implement policy and management measures, explore policy options, inform policy evaluations, and apply in learning processes between policy-makers, scientists and stakeholders – are not fully exploited. The aim of this dissertation is to increase our understanding of the interaction problems science and policy face, and the extent to which science–policy interfaces could contribute to eliminating these problems and enriching decision-making. Science–policy interfaces can be organisations, individuals or objects, which are placed (or place themselves) at the boundary between science and policy with the aim of enhancing the interactions and enriching decision-making processes by the use of scientific knowledge. Following the scholarly literature in this subject, in order to be used in environmental decision making and to enrich it, science must meet three criteria: it needs to be perceived as credible (scientifically valid) and salient (relevant to decision makers), and to have been produced in a way that is seen as legitimate by all stakeholders involved. The empirical focus of this research is on the Dutch Wadden Sea, an area in which the ecological and ...