Vincent Ferraro, "Dependency Theory: An Introduction, " in The Development Economics Reader, ed. Giorgio Secondi (London: Routledge, 2008), pp. 58-64
Dependency Theory developed in the late 1950s under the guidance of the Director of the United Nations Economic Commission for Latin America, Raul Prebisch. Prebisch and his colleagues were troubled by the fact that economic growth in the advanced industrialized countries did not necessarily lead to growth in the poorer countries. Indeed, their studies suggested that economic activity in the richer countries often led to serious economic problems in the poorer countries. Such a possibility was not predicted by neoclassical theory, which had assumed that economic growth was beneficial to all (Pareto optimal) even if the benefits were not always equally shared.
Prebisch's initial explanation for the phenomenon was very straightforward: poor countries exported primary commodities to the rich countries who then manufactured products out of those commodities and sold them back to the poorer countries. The "Value Added" by manufacturing a usable product always cost more than the primary products used to create those products. Therefore, poorer countries would never be earning enough from their export earnings to pay for their imports.
Prebisch's solution was similarly straightforward: poorer countries should embark on programs of import substitution so that they need not purchase the manufactured products from the richer countries. The poorer countries would still sell their primary products on the world market, but their foreign exchange reserves would not be used to purchase their manufactures from abroad.
Three issues made this policy difficult to follow. The first is that the internal markets of the poorer countries were not large enough to support the economies of scale used by the richer countries to keep their prices low. The second issue concerned the political will of the poorer countries as to whether a transformation from being primary products producers was possible or desirable. The final issue revolved around the extent to which the poorer countries actually had control of their primary products, particularly in the area of selling those products abroad. These obstacles to the import substitution policy led others to think a little more creatively and historically at the relationship between rich and poor countries.