This is a thorough revision and updating of the standard work Theory of Thermal Neutron Scattering, and includes 40% new material. There are completely new chapters of quantum fluids, multi-component liquids and diffuse scattering, and a greatly expanded bibliography with over 200 new references. The two volumes develop the principles and concepts of statistical physics and quantum chemistry that are the basis for the interpretation of experimental data. Volume 1 deals with elastic and inelastic events in scattering from nuclei, and Volume 2 covers electron plasmas and magnetic ions. 'A very useful work of reference... will be consulted by neutron scatterers for many years.' Nature