This title was first published in 1968. Economic development and the system of the functioning of socialist economies have become the subject matter of an increasing number of works by economists throughout the world. Indeed, the experiences of socialist countries on different levels of social and economic development already offer a good deal of empirical material for theoretical analysis. An attempt at such an analysis has been made in this book, where the authors have concentrated on the investigation of a specific phenomenon in the motion of the economy — so-called investment cycles.