No cure has been found for HIV/AIDS. Therefore, until one is found which is affordable and feasible for use in developing countries, preventing HIV infection is the best way to combat the HIV/AIDS pandemic. All of the many biological characteristics of HIV which affect its rate of spread in a population can be affected through individual behavior. The two most important behaviors which spread HIV are having sexual intercourse with an HIV-infected sex partner without using a condom and sharing unsterilized drug injecting equipment. Strategies to reduce risky behavior include providing information, lowering the costs of condom use and safe injecting behavior, and raising the costs of risky behavior. The costs of condom use include the financial and time costs of buying the condoms, the potential inconvenience and social embarrassment of buying and using them, and reduced pleasure among some users. IV drug users face the problems of getting into and remaining in drug treatment programs, and obtaining sterile injecting equipment. Government priorities in preventing HIV/AIDS and mobilizing political support against AIDS are discussed.