Considerable variation in behavior among drug injectors and noninjectors in different cities over time complicates an understanding of the dynamics of drug use. AIDS has prompted many intravenous drug users to change their behavior, although not all users have reduced the risks of transmitting HIV infection. While expanded harm reduction and drug abuse treatment strategies may limit the epidemic's spread, weak Federal support, constrained hospital resources, and racial stigma inhibit more direct action needed to stem negative social and personal consequences of drug use. More effective government responses to AIDS transmission via intravenous drug use are needed. If it is true that despair, shame, and alienation are major causes of drug use, policies to deal with AIDS should target these causes. Government policies, therefore, should reduce racism, increase employment in good jobs that can be filled by the poor, and reduce social sources of alienation. The social situation of intravenous drug use is discussed, along with effects of AIDS on intravenous drug user behaviors, racial differences in risk reduction and knowledge, and social relations and pharmacology of cocaine injection. 63 references and 1 table