This study has been written during my time at the Institute of Public Finance at the Albert-Ludwigs-University of Freiburg, Germany. I am indebted to a number of people who have made this work possible. First and foremost, I thank my teacher Prof. Dr. Bernd Raffelhuschen with whom I had the pleasure of working for many exciting years. The German term "Doktorvater" alludes to the fatherly role of a thesis supervisor, and he has truely lived up to this role. Also, I am grateful to Prof. Dr. Dr. h. c. Hans-Hermann Francke for his co-correction and the valuable comments he has given me. In addition, I wish to thank my family. Especially, my wife, Daniela, has not only supported me with her love and affection but has also kept an eye on my discipline when the going got tough. The greatest sacri?ce in the course of working on this thesis, have been the miles and many hours away from her. Unfortunately, the yearsofmydoctoralstudieswereovershadowedbythedeathofmyfather. Tohimand mymother,Eva-MariaBorgmann,Iamimmenselygratefulfortheirloveandsupport throughout my life. Daniel Besendorfer and Erik Luth have been close companions and friends at the Institute of Public Finance from my ?rst days in Freiburg, and I have gained from their friendship enormously. This work has largely pro?ted from comments and suggestions of many colleagues who have also been great fun to work with. Among them, I especially thank Holger Bonin, Oliver Ehrentraut, Matthias Heidler, Stefan Fetzer, Pascal Krimmer, and Stefan Moog.

Inhalt
Fundamental Results on Social Security in a Deterministic Economy.- Social Security and Demographic Transition.- Old-Age Provision and Uncertainty: An Introduction to Issues of Risk and Risk Sharing.- Labor Income Risk, Demographic Risk, and the Design of (Wage-Indexed) Social Security.- Demographics and Political Risks of Benefit Rule Changes: A Case Study for Germany.- Social Security, Portfolio Choice, and Financial Markets.- Conclusion.