This study was accepted as a doctoral thesis by the Department of E- nomics of the Johann Wolfgang Goethe-University in Frankfurt/Main. It was undertaken within the research project 'The E?ects of Job Creation and Structural Adjustment Schemes on the Participating Individuals', which was conducted by the Institute of Statistics and Econometrics (Empirical E- nomic Research) in cooperation with the Institute for Employment Research in Nuremberg. I have to thank numerous people. First of all my thesis supervisor, Prof. Dr. Reinhard Hujer, for initiating this thesis and providing me with a great scienti?c environment. I owe the data I used to his persistent lobbying to promote and anchor evaluation research in Germany. I am also very grateful to Prof. Dr. Roland Eisen who did not hesitate to act as the second thesis supervisor. Thanks also to Christian Brinkmann and his team at the Institute for Employment Research (Institut fur ] Arbeitsmarkt- und Berufsforschung) for valuable help with the datasets. Ihavealsobene?tedfromcontinualdiscussionswithmycolleaguesStephan L.(!)Thomsen, DubravkoRadic, PauloRodrigues, SandraVuleticandChris- pher Zeiss. A warm thanks goes also to Birgit Kreiner and all our current and former student research assistants.