This is the second volume of a two-volume text on the scattering of x-rays and thermal neutrons from non-ideal (real) crystals. It deals with equilibrium fluctuations in the various order parameters of a crystal including concentration, positional, and orientational fluctuations, considering also the variety of interactions responsible for the observed (diffuse) scattering patterns. Both theoretical and experimental situations are treated and a wide range of solids, including metals, alloys, semiconductors, and insulators are covered. As we come increasingly to appreciate the importance of disorder in solids, this book will become an indispensable guide to the study of disordered crystals.