The study will combine individual-level medical outcome and treatment cost data from the treatment program with data on employee work attendance and retention in the workforce from the participating employer. The work attendance of HIV infected employees enrolled in the HIV/AIDS treatment program (index participants) who are either taking ART or receiving pre-ART care will be compared with each other and with that of HIV uninfected employees. There are no study visits associated with this study; all data will be collected from medical records maintained by the HIV/AIDS treatment program and the participants' employer. The financial costs and benefits of the treatment program for the participating company will also be estimated.