AIDS, which is caused by infection with HIV, is associated with many deaths and occurrences of disease. Although recent advances have been made in anti-HIV therapy for AIDS, there is no cure for HIV infection or AIDS, and drug therapy is too expensive for most infected populations. Some organizations are trying to make safe and effective vaccines that may prevent HIV infection and AIDS worldwide. Certain vaccines can generate specific antibodies in humans, but they do not inhibit HIV infection in laboratory tests. It is possible, however, that these antibodies may make HIV disease less severe following infection. For this reason, monkeys will be used to evaluate the role of specific human antibodies.