This paper deals with the issue of black-white differences in cognitive skills. Some authorities attribute these differences to differences in the environments of black and white homes. Others state that the differences are due to differences in genes, i.e., heredity. Scholars holding these two opposing views have become more or less entangled in an endless debate since Jensen published his article in 1969. The purpose of this paper is to suggest an alternative, structural explanation. The hypothesis proposed here is that black-white differences are due to adaptation to different cognitive requirements of their respective positions in the American caste system. In particular, it argues that the ascribed status of blacks which restricts them from participating in higher levels of American techno-economic organization has resulted in blacks evolving patterns of cognitive skills which are different from those developed by white Americans. This hypothesis has the advantage in that it can be applied to explain the observed differences between black males and black females as well as to minority-majority differences in other societies where similar pariah groups exist. Its significance for social policy lies in the fact that it identifies the cause rather than the symptoms of black educational problems. (Author/JM)