On October 18th and 19th, 2002, a colloquium was held at the Freie Universität in Berlin, visited by an international group of about 60 scholars to present and discuss current research from social sciences regarding the potentials and restrictions of pioneering behaviour of states in environmental policy. The colloquium was funded by the Fritz Thyssen Foundation. It was organised on the occasion of the 65th birthday of Prof. Martin Jänicke in August 2002. The primary aim of the conference was to combine different streams of research that are yet independent in order to identify synergies for future research. In detail, these were research approaches that, (1) search for the national characteristics and conditions for pioneering behaviour, (2) ask for the international conditions and (3) analyse the economic conditions and implications of a vanguard role in environmental policy. The focus was primarily on contributions from political science. It was largely consensus that pioneering behaviour is a critical influencing factor for the advancement of European and international environmental policy. It was conceded, that despite the advancing internationalisation of political law and decision making there is still room for manoeuvre for an ambitious national environmental policy. Beyond that, states may possibly enhance their capacity for action by a skilful management of interdependencies in international regimes and organisations. This can be indicated by the growing importance of the Scandinavian countries for the world wide development of environmental policy. It has to be mentioned though regarding the state of the art in social sciences, that there are neither generally accepted criteria of analysis for the empirical determination of pioneering behaviour, nor for the investigation of the relevant causal factors and impacts of such a behaviour. As a matter of fact, different definitions, perspectives for analysis and methods of measurement are applied, that have to be clarified and coordinated mutually in order to develop a consistent framework of analysis that can be utilised for empirical investigations in cross country comparative research. In the course of the colloquium, the outline for such a framework has been identified and discussed regarding forthcoming research. It is planned to publish the contributions to the project in a conference report.