In this volume a large number of renowned researchers and policy-makers discussed a broad range of topics. Together they offer as complete a picture as possible of the costs and benefits of collective pension systems. The concept of solidarity was extensively examined and the extent to which the existing types of solidarity play a role within collective pension schemes was analysed. Now it is clear where the inherent costs of these systems lie and which elements are responsible for the benefits. Where possible, these aspects are quantitatively substantiated. A debate that is based on facts is preferable to ignorance. In this book, we aimed to present sufficient clarity and factual material, so that the discussion concerning the costs and benefits of collective pension schemes can be continued at a higher level.