The collection of essays is entitled Challenges Ahead'. An ambitious title, but an appropriate one; for the contributors, as the 21st century draws near, ask themselves a number of basic questions about the future of the law in a world undergoing such profound changes. Their reflections will certainly give both cause for hope and reason to fear. This "Liber Amicorum" dedicated to Professor Frits Kalshoven, is written by specialists who for many years have given their best to the development and promotion of humanitarian law. It will make a significant contribution to the understanding of international humanitarian law.