After twelve years as Co-Director of the Project on Internal Displacement at the Brookings Institution, Roberta Cohen retired at the end of 2006. This special issue not only commemorates Roberta’s work but also takes stock. The articles explore lessons learned from trying to apply the Guiding Principles, the implications of institutional changes for the protection of IDPs and opportunities and challenges for putting the protection of IDPs into practice. The authors remind us how much progress has been made and the importance of Roberta’s contribution. However, they also warn us how much remains to be done.