Impact analysis of economic policy is a subject which is gaining in- creasing interest in both theoretical and applied economic research. Two main reasons for the growing interest can be distinguished. First, the situation of the government's finances is making it more than ever necessary to assess critically the effects of the instruments used to pursue public policy goals. Secondly, because of the economic stagnation government will be increasingly appealed to for support. Impact analysis, however, is hampered by three major problems: methodological deficiencies, lack of econometric approaches which have been adapted to the specific conditions of this kind of analysis and data availability. The present book deals with these problems in the context of regional economic policy. However, the main findings are broadly applicable in various other fields. This book is primarily oriented towards those who have a practical interest. Therefore, attention is mostly paid to the practical aspects of the methodology and the measurements methods. Furthermore, the methodologi- cal and econometric parts are supplemented by two extensive case studies. - Three people have contributed constructive criticisms and suggestions on some chapters of the book: Peter Nijkamp, Theo Dijkstra and Manfred Fischer. I am very grateful for their support. They, of course, share no blame for any deficiences in the present form of the book. I also gratefully acknowledge the assistance of Harry Barkema and Marja Schuring with the computations.