The subject of the book is electron transfer reactions in organic chemistry, with the emphasis on mechanistic aspects. The theoretical framework is that of the Marcus theory, well-known from its extensive use in inorganic chemistry. The book deals with definitions of electron transfer, theory of electron transfer reactions (Marcus' and Pross-Shaik's approach) experimental diagnosis of electron transfer reactions, examples from inorganic/organic reactants and purely organic reactants, electro- and phohemical electron transfer, electron transfer catalyzed reactions, connections between electron transfer and polar mechanisms, and applications of electron transfer, such as electrosynthesis of organic chemicals, phohemical energy storage, conducting organic materials and chemiluminescence. The approach is new in so far as no comparable book has been published. The book will be of value to anyone interested in keeping track of developments in physical organic chemistry.