This report presents demographic data for four racial populations in South Africa (Blacks, Whites, Coloureds, and Asians) and examines trends in the aging of each of these populations. The age structure of a population is determined most directly by fertility and mortality. The findings of this report support a general theory to the effect that the average age of a population eventually rises in the transition from high to low levels of fertility and mortality. The report shows that the four South African populations are at different stages of this demographic transition. Whites are at the most advanced stage in this process, and are characterized as demographically old; the median age of this group was 29.5 years in 1985. Blacks, on the other hand, are demographically the youngest population group with a median age of 17.9 years in 1985. Asians and Coloureds occupy intermediate positions; in 1985 their median ages were 23.3 and 21.3 years respectively. While the demographic age of Blacks will eventually undergo the same transition, it is likely to be much less rapid than the transition of the other three groups, whose aging is projected to advance at steady rates. Numerous figures and tables of demographic data appear throughout this report, and a 22-item list of references is included. (DB)