This book describes for the first time in a modern text the fundamental principles on which solid state chemistry is based. In this sense it differs from other books on the subject, which tend to concentrate only on a description of materials. Topics include solid (ceramic) electrolytes, glasses, polymer electrolytes, intercalation electrodes, interfaces and applications. The different nature of ionic conductivity in ceramic, glassy and polymer electrolytes is described, as are the thermodynamics and kinetics of intercalation reactions. The interface between solid electrolytes and electrodes is discussed and contrasted with more conventional liquid state electrochemistry. The text provides an essential foundation for postgraduates and others entering the field for the first time and will also be of value in advanced undergraduate courses.