Some of the important policy and research implications of accumulating HIV/AIDS data are being ignored because of the attraction of social science research focused on the ‘multiple sexual mechanism’ of infection and transmission. Attention is drawn to the other policy and research issues relating to information on the timing of infection through a reanalysis of existing data on cumulative AIDS cases. The most urgent need is to supplement the mainstream research on risk groups with studies of the timing and circumstances of entry into sexual activity in the pre-teen years.