The Government of the Republic of South Africa is implementing a national program to provide antiretroviral therapy (ART) to all eligible HIV infected South African adults. While the medical effectiveness of ART in suppressing viral replication is well established, little is known about the economic effectiveness of treatment. In particular, it is not known if treatment will offset the impact of HIV/AIDS on labor productivity, household stability, quality of life, and other aspects of social and economic development. The purpose of this study is to estimate the impact of ART on the productivity, economic welfare, and quality of life of adult HIV infected patients in South Africa. The study will investigate: