The recognition of HIV as the etiological agent responsible for AIDS quickly led to a serologic test and a misplaced belief that a preventive vaccine would soon follow. However, the search for a vaccine has led to an explosion in knowledge about the behavior and biology of HIV transmission by all routes. This information has informed development of other interventions: safer sex behaviors, condoms, and better treatment of STDs. Alternative biological interventions, including protective microbicides and antiretroviral agents, are progressing rapidly. From this review it should be clear that biomedical and behavioral approaches to HIV prevention are being simultaneously developed. The biomedical interventions cannot be implemented without the behavioral change components to support and amplify them. The tools to prevent HIV transmission are being forged. It seems likely that their application will slow the spread of the epidemic until curative therapy becomes available.