The importance of social networks is increasingly being recognized in research on HIV risk behaviors. The objective of this article is to examine the association of AIDS and sexually transmitted disease (STD) knowledge, perceived susceptibility to HIV/STD infection, condom beliefs, demographic variables, and peer influence on the condom use of clients of Indonesian sex workers. Data for the study are drawn from the Bali STD/AIDS study conducted from 1997 to 1999 in Bali, Indonesia. During the project 2,026 men were selected for interviews in low price brothels. Statistical methods included multivariate regression models. Results of the study showed that younger men, men who have resided in Bali for at least a year, and more educated men were more likely to use condoms. Furthermore, men with stronger AIDS and STD knowledge and condom beliefs were more likely to use condoms. Men whose friends knew that they visited sex workers were less likely to use condoms. However, men who reported that their friends used condoms with sex workers and that their friends encouraged them to use condoms with sex workers were more likely to use condoms with sex workers. Implications for prevention of HIV infection are discussed.