AbstractScientific expertise is necessary in the policy arena to replace the previous trial-and-error regime. It can offer enlightenment, instrumental or pragmatic knowledge, reflection, and catalytic process promotion. Four styles of using scientific expertise can be distinguished: adversarial, fiduciary, consensual and corporatist. A new mediative style results from the current, more open procedures in decision-making. Europe's strength in using scientific expertise depends on a more ‘system- and problem- oriented’ approach in which science, politics and economics are linked by strategic networks.