In 2004, the Major Accidents Hazards Bureau of the Joint Research Centre of the European Commission launched the “Land Use Planning Including MAHB and NEDIES” research programme, in the context of which most of the research collected in this book was conducted. The focus of the investigation was on the different methods developed by Member States for implementing Art 12 of the Seveso II Directive, stating the Control of Urbanization requirement. Art 12 is the first European requirement calling Member States to “ensure that the objectives of preventing major accidents and limiting the consequences of such accidents are taken into account in their land-use policies and/or other relevant policies”. Scope of the MAHB investigation was providing an up-to-date overview of national implementations of Art 12 in order to elaborate the relevant Guidance and providing Member States with additional supporting instruments. The Guidance was adopted by the European Commission in November 2006. Based on a questionnaire survey, literature review and direct interviews with the members of the European Working Group on Land Use Planning (EWGLUP), the investigation led to the elaboration of a second supporting instrument, the Roadmaps. In this research document, the different methods developed in a selected group of Member States (The Netherlands, the United Kingdom, Germany, France and Italy) for implementing Art 12 are investigated. Recommendations for best- practice in the field are given. In the autumn of 2004 the PhD project was involved in the investigation and particularly in the elaboration of the Roadmaps. But whereas this research document ended with reporting the different approaches developed in the European Union, the PhD project tried to explain them. Which are the characterizing elements of the different national implementations of Art 12? What determined the development of different methods for land use planning in “Seveso” areas in the relevant national practices? Are different national approaches leading to different levels of prevention? How are political views and cultural orientations influencing their adoptions? Finally, which is the role and which are the perspectives of the European regulation in the light of these differences?