The communists' preoccupation with economic growth and their whole attitude towards economic progress have been shaped by Marx's theory of long-run development of human society. This theory places economic development at the center of the entire social philosophy and it is impossible to study the Marxists' political, social and economic views without referring to it. Without the knowledge of this theory it is difficult to understand the communists' dogmatic belief in the superiority of their system, whatever are the observable facts, and their faith in the final victory over capitalism. Economic development has to lead, sooner or later, to socialism and communism and it is necessary to build socialism and, later, communism to make future economic growth possible. This principle is valid for all countries without any exception. They all have to proceed along the same path although they may be placed at different points of it at present. Such is the logic of history. This theory, which is usually referred to as 'historical materialism', 'the materialistic conception of history', or 'Marx's historical determinism', is believed by Marxists to be useful not only as the explanation of the past and the present but also as the basis for the prediction of the future course of history. As the final judgment on any prophecy has to be made in the light of the subsequent events, it is interesting to compare the developments since the theory was presented by Marx with the pattern which could have been expected on the basis of Marx's prediction. The purpose of this paper is to outline briefly such a comparison and to discuss the communist explanation of the disparity, which had appeared between the actual and the predicted course of events. The paper does not attempt to evaluate the philosophical aspects of the theory, its materialism, one-sidedness and methodological oversimplification. Similarly, the value of the theory as a summary of the past historical events preceding the time when it was presented by Marx and its merits and weaknesses as one of the numerous 'stages of growth' theories are not discussed. Marx's theory accepts as its basis that man's life is a conscious struggle with the natural environment, the struggle which takes the form. of production as 'life involves, before everything else, eating and drinking, a habitation, clothing, and many other things'. The process of production is the interaction between man and nature and it takes the form. of social labor. Man has to improve his instruments of production in order to master the natural environment but 'the development of these instruments follows a definite sequence' as 'each new improvement and invention can be made only on the basis of those that have preceded it, and must rest upon gradually accumulated production experience, the labor skills and knowledge of the people... '. Production is carried on as a social process, because 'in the process of producing material wealth, people, whether they like it or not, find themselves in some way linked with another and the labor of each producer becomes a part of the social labor.' These relationships among men are called the 'relations of production'. They exist independently of human consciousness and this gives them their materialistic character. They are determined by the level of development and the nature of productive forces. (546) The author indicates that the typical communist ______.