The idea of writing a book on neutron scattering from magnetic materials occurred to me about four years ago. I was then acting as a subeditor of the topic Neutron Scattering for the encyclopedic book “Scattering: Scattering and Inverse Scattering in Pure and Applied Science” which was to be published by Academic Press, London [1]. There I had to cover the field of neutron scattering in a very limited space and that was a very difficult and frustrating task indeed. I