For over a decade, many businesses have experienced increased costs and reduced productivity as a result of HIV/AIDS. Many companies are responding to the HIV/AIDS crisis through investment in prevention programs, especially in employee education and condom distribution. A smaller, but increasing number have supported a range of care and treatment services for employees and their families. However, not enough is known about the factors that influence the choices companies make in HIV/AIDS service provision and the range of approaches taken to increase access to services. To address this knowledge gap, the Private Sector Partnerships-One project (PSP-One) conducted a survey of companies in Ethiopia, Kenya, Namibia, and Zambia in 2006-2007. PSP-One selected the sample based on a list of companies that donor agencies had previously worked with related to HIV/AIDS issues. Human resources personnel or health clinicians from 121 companies participated in the survey via an online, self-administered questionnaire, or phone interviews. The data were then analyzed using univariate and bivariate analyses. Additional qualitative data were collected through key informant interviews with company personnel from four companies in each of the study countries.