The initial idea of having a volume of International Tables for Crystallography dedicated to the physical properties of crystals is due to Professor B. T. M. Willis. He submitted the proposal to the Executive Committee of the International Union ofCrystallography during their meeting in Vienna in 1988. The principle was then adopted, with Professor Willis as Editor. After his resignation in 1990, I was asked by the Executive Committee to become the new Editor. Following a broad consultation with many colleagues, a nucleus of potential authors met in Paris in June 1991 to define the contents of the volume and to designate its contributors. This was followed bya meeting in 1995, hosted by Theo Hahn in Aachen, of the authors contributing to Part 3 and by another meeting in 1998, hosted by Vaclav Janovec and Vojtech Kopsky ´ in Prague, of the authors of the supplementary software.