The science of semiconducting materials is still very young. Less than twenty years ago, the school of A. F. loffe demonstrated that the properties of semiconductors are governed primarily by their chemical nature and can be predicted on this basis. These ideas are still be­ ing developed and used to establish a new materials science: the chemistry of semiconductors. The solution of problems in the chemistry of semiconductors should make it possible to find new applications for solids. We are already witnessing the process in which the practical importance of such new materials as diamond-like AlIIB V compounds is accelerating the de­ velopment of the chemistry and phYSics of semiconductors and some allied sciences. Diamond-like semiconductors are promising materials for modern electronics. They be­ long to an extensive class of valence compounds which seem to be an inexhaustible source of new semiconducting materials. Among these new, particularly promising materials, are ternary diamond-like semicon­ ductors, which are the subject of the present monograph. The appearance of this book, which is the first on this subject not only in the Soviet Union but also outside it, is the proof of the im­ portance attached to promising semiconductors in the USSR. The authors describe the methods for the preparation of compounds and the growth of single crystals. They analyze in detail the phYSicochemical and phYSical properties of ternary compounds and the relationships between these properties, and consider the possible applica­ tions of these substances and suggest further investigations.