In both industrial and developing societies, the school has become an important link between an individual's family of origin and occupational attainment. More often, cognitive achievement as determined by examination results is used to allocate starting points in the occupational hierarchy. Perhaps the most significant attempt to explain how schooling functions as an intervening mechanism is the research tradition of William H. Sewell, A.O. Haller and G. Olendorf at the University of Wisconsin.' The purpose of this paper is to establish the extent to which the socio-economic background and other intervening factors continue to influence cognitive ability and achievement in Indonesia. The first part of the paper provides some brief comments on comparative research in non-western countries. The second part elaborates on the data and measures used in the case of Indonesia. The final section reports the finding for cognitive ability and achievement among 9,751 ninth grade students in Indonesia.