This article describes the second stage of a research project on sexual networking that aims to further understanding of the spread of sexually transmitted diseases and HIV/AIDS in Ondo State, Nigeria. A sample of 488 males aged 15-50 were interviewed in depth to ascertain (1) the numbers and characteristics of their sexual partners, (2) the numbers and characteristics of the partners of those partners, and (3) the extent to which these relationships were commercial. In addition, a census was taken of all commercial sex establishments in order to estimate the numbers of their clients. The results show that male (and female) sexual networking is extensive, that in most nonmarital relationships men do not have accurate knowledge of their partners' partners, and that detailed questioning provides a reasonably accurate picture of the number of these relationships that are commercial in nature. The situation revealed was one of sexual diffusion rather than one with a strong focus on commercial sex workers, which fits the model of a slowly increasing HIV/AIDS epidemic rather than an explosive one.