About a decade ago, the Netherlands Environmental Assessment Agency (PBL) unwittingly embarked on a transition from a technocratic model of science advising to the paradigm of “post-normal science” (PNS). In response to a scandal around uncertainty management in 1999, a Guidance for “Uncertainty Assessment and Communication” was developed with advice from the initiators of the PNS concept and was introduced in 2003. This was followed in 2007 by a “Stakeholder Participation” Guidance. In this article, the authors provide a combined insider/outsider perspective on the transition process. The authors assess the extent to which the PNS paradigm has delivered new approaches in the agency’s practice and analyze two projects—on long-term options for Dutch sustainable development policy and for urban development policy—the latter in somewhat more detail. The authors identify several paradoxes PBL encounters when putting the PNS concept into practice. It is concluded that an openness to other styles of work than the technocratic model has become visible, but that the introduction of the PNS paradigm is still in its early stage.