The papers are generally available only in their original language - English or French -with a summary in the other. We thank Michael Forster for helpful discussions as well as Tony Atkinson, Brian Nolan, Markus Jantti, Timothy Smeeding and colleagues from the OECD Economics Department and the Directorate for Employment, Labour and Social Affairs for providing us with valuable comments at different stages of the drafting process. This working paper should not be reported as representing the official views of the OECD or of its member countries.