This publication contains the proceedings of the World Forum on Key Indicators held in Palermo in November 2004. In it, statisticians from governmental statistical offices, international organisations, and academia explain why indicator systems are useful and how statistics can be used, how to implement systems related to different kinds of statistics, and what systems are already in place. This conference was the first co-ordinated world wide effort to study the development and implications of large-scale systems of public information for developed countries.