The operation of a powder mixer requires a knowledge not only of the mixing mechanisms but of the physical properties of the powders being mixed. This text begins with a review of the different types of mixer used to achieve an intimate mixture. It explores the relevant physics of the powder systems, including characterization procedures and rheology, and contains a review of the different methods that have been employed to study the structure of mixtures. The techniques for achieving structured mixtures such as micro encapsulation, and recent developments in deterministic chaos theory and fractal geometry applied to the study of powder mixing systems are reviewed. In particular, new techniques for studying the mixing of powders based on avalanching theory and critically self-organized systems are studied. These are followed by a review of the wide range of different mixers commercially available. This volume should be of use to all those interested in the basic science of powder mixing and the availability of industrial systems to achieve mixtures of different kinds. The main emphasis of the text is on working principles and operative systems, making it suitable for industrial workers, chemical engineers and students alike.