All correspondence to Espen Bratberg. We are indebted to the referees for detailed remarks, which significantly improved the paper. Financial support from the Norwegian Research Council and the Ministry of Health and Social Affairs is greatly appreciated. We are grateful for valuable comments from Erik Hernæs and Astrid Grasdal, seminar participants at the Norwegian School of Management in Oslo, the Institute for International Economic Studies in Stockholm, and the University of Linz, the 2000 Conference of the European Society for Population Economics in Bonn, and the German-Norwegian Seminar on Social Insurance in Berlin, 2000. Bratberg would also like to thank the Humboldt University for its hospitality during a stay in the winter of 2003. Responsible editor: Christoph M. Schmidt.