First of all, I would like to thank my supervisor, Prof. Dr. Ursula Renold, for the opportunity to write this thesis under her supervision, for her advice, support and constructive feedback. Thank you for always being motivating, and for conveying your passion and enthusiasm for vocational education and training. I would also like to thank Prof. Dr. Stefan C. Wolter for acting as co-examiner and for all valuable comments received on the final version of the thesis, but also at earlier stages.I am deeply indebted to Thomas Bolli, for being an excellent co-author, but especially for always being available for any discussion and exchange. In working with you, I have learned the importance of methodology and logical argumentation in conducting economic research. Without you, I probably never would have completed my PhD.I am very grateful to current and former members of the Chair fo Education System (previously Comparative Education Systems Research Division at KOF Swiss Economic Institute) for offering me an ideal environment for research. I especially appreciated the great collaboration and team spirit that characterized these years together. I would also like to thank several colleagues at KOF, with whom I had fruitful exchanges, but especially I spent pleasant moments together.This dissertation has been partly been funded by the Swiss State Secretariat for Education, Research, and Innovation, for which I am grateful. I also highly appreciate the provision of data by various institutions and the valuable comments that I received in a number of conferences, seminars, and workshops.I further thank both the organizers and the participants of various courses at the ETH Zurich and at the University of Zurich for creating an excellent learning i environment. In particular, I appreciate the possibility to attend the Course Programme for Doctoral Students in Economics of Education jointly organized by Prof. Dr. Uschi Backes-Gellner and Prof. Dr. Stefan C. Wolter.Finally, I would like to thank my family and friends for always being there for me. A special thank goes to my girlfriend Aline, for always supporting me in the choice to do a doctorate.