vorgelegt von

This dissertation is the result of the last three years which I spent as a fellow of the DFG-Research Training School Group-Focused Enmity at the Philipps-University of Marburg and the University of Bielefeld. At this point I would like to take the opportunity to thank all the people who supported me and my research during this period. First of all, I would like to thank my supervisor Peter Schmidt and Ulrich Wagner for their professional and personal advice in writing this dissertation. Furthermore, I would like to thank all my colleagues and staff members of the Group-Focused Enmity Research Training School for the good cooperation, in particular Johannes Ullrich and Oliver Christ for sharing theoretical and methodological inspiration, hotel rooms and drinks which made our – various – lecture tours worthwhile. I would also like to thank Reiner Becker not only for technical support, Eldad Davidov, Sabine Manke for sharing the burden associated with the ‘D-word ’ and help, Olaf Sosath and Martin Klehr a.k.a the Computer Squad for saving my data and myself more than once, and Antje Klug