HPTN 063 was a research study to conduct the preparatory research needed to design a behavioral intervention to decrease sexual transmission risk behaviors in HIV-infected individuals in care and to determine whether a similar intervention structure could be used across various sexual risk groups and cultural settings. A total of 751 HIV-infected participants (200 MSM in Brazil and Thailand, 300 heterosexual women, and 251 heterosexual men in Brazil, Thailand, and Zambia, who had reported recent (within in the last three months) HIV sexual transmission risk behavior. Study participants completed five quarterly quantitative surveys over the course of a year, and provided specimens for sexually transmitted infection analysis.