Two general questions stood at the beginning of this PhD-thesis, namely: • What are the mechanisms which lead to the emergence and establishment of new technologies? • How can this process of technological change be influenced politically? In this sense, conceptual and theoretical interests were the early driving forces of the research work. This is also reflected in the considerable attention paid to the nature of technological change and political control. The result is an holistic per­ spective which builds on inputs from different disciplines and aims at dynamic interpretation. This, however, created a severe methodological problem: How could such a comprehensive perspective be used constructively? To develop this link between theory and forward-looking, policy-oriented analysis, and to devise a methodology which showed explicitly how this approach could be used in a constructive way were in fact the major challenges of this research project. The appli­ cation to the example of combined heat and power generation, and the comparison of the developments in the UK and in Germany serve the purpose to demonstrate how this approach and methodology can be implemented in practice. These as­ pects were also of particular interest to the Institute for Prospective Technological Studies (IPTS), one of the institutes of the European Commission's Joint Research Centre, where most of the research work reported in this PhD-thesis was carried out.