The purpose of this article is to set forth the features, relations and fundamental problems which characterize peripheral development. The analysis principally seeks to throw light on the mechanisms underlying the distribution of the fruits of technological progress among the different social strata. To this end, a detailed account is given of the process of creation of the surplus and of its primary appropriation by the upper strata (through the power deriving from their ownership of the means of production), and its secondary appropriation by the middle strata (which are favoured by democratization).