This article describes policy–science interactions in a transition process in which we were involved as scientists. We describe the interactions that occurred in a project for the fourth National Environmental Policy Plan in the Netherlands. The project was successful in that it produced a new concept and set of principles for policy to deal with persistent problems such as global climate change, which were used in the national policy plan. The new concept was that of transition and the principles were: policy integration, long-term thinking for short-term action, keeping multiple options open and learning-by-doing and doing-by-learning. Retrospectively, we ask ourselves: what factors facilitated the acceptance of the first ideas about transition management? Reconstructing the events and drawing on interviews with key individuals involved, we have tried to find the key factors for the adoption of the ideas developed in the project. Finally, we reflect upon our role as scientists-advisors and the role of others in the development of a new story line and set of principles for policy. Our own assessment, 8 years later, is that we were engaged in boundary work.