This article illuminates the contribution of stakeholder dialogues to environmental policy making. It makes a distinction between stakeholder dialogues as consensus building and stakeholder dialogues as deliberation. Although consensus building seems to be the dominant approach in participatory environmental policy making, this article questions the merits of consensus building and it uses the experience of the Dutch stakeholder dialogue project Climate OptiOns for the Long term (COOL) to explore, in a deliberative design, the shortcomings of a consensus-building approach and how they are possibly dealt with. The article presents the results of two deliberative methods that have been used in the COOL project - the repertory grid analysis and the dialectical approach - to demonstrate how a deliberative design can help policy makers to critically assess arguments in favor of and against a broad range of policy options, and deal with stakeholder conflict in an early phase of the policy process. © Springer Science+Business Media, LLP 2006.