Initiation of antiretroviral therapy (ART) in the HIV infected population has been shown to dramatically reduce the morbidity and mortality of HIV infection through sustained reduction in HIV viral replication. However, such therapy does not cure HIV infection or prevent the spread of the virus. ART may, however, make HIV infected people less contagious by lowering plasma HIV-1 RNA levels, compared with people not on ART. This study seeks to determine whether initiating ART in ART-naive, HIV infected people can prevent the sexual transmission of HIV among HIV-discordant couples, as well as to demonstrate whether quality of life changes with the initiation of ART. Both opposite and same sex couples will be recruited at study sites in Brazil, India, Malawi, Thailand, the United States, and Zimbabwe for this study.