A book written by a well-known American expert in the field of photoconductivity and luminescence P. Byubom, is the first monograph in the world literature, which sufficiently fully and consistently describes all the main aspects of photoconductivity. The author focuses on the physical essence of the phenomena under consideration and those theoretical ideas that are attracted to explain them. The great advantage of the book is that it contains a huge factual material about the properties of almost all known and of scientific or practical interest photoconductive substances. The latter allows the book to be used as a reference tool. A special place in the book is occupied by a description of the methods of chemical preparation of photoconductive substances. The book is intended for a wide range of scientists and engineers dealing with various studies of the phenomenon of photoconductivity and numerous technical devices in which this phenomenon is used. The book can also serve as a manual for senior students of universities specializing in semiconductor physics and engineering ..