The injection of psychoactive drugs is more widespread than ever before and is now practiced in more than 80 countries on six continents. Intravenous drug use has remained widespread despite decades of intense efforts by law enforcement agencies around the world. Nevertheless, in some localities and countries, a broad variety of programs have had some success in reducing AIDS transmission among intravenous drug users. At the individual level, drug treatment is effective. Harm-reduction strategies have been the most effective approaches in cities and countries. Needle-exchange programs have been a major focus of harm- reduction programs. Drug abusers themselves have been important in organizing to prevent HIV; tuberculosis is a particular concern among drug abusers. Repressive drug policies have provided social elites with scapegoats, a method for dividing economically powerless people, a rationale for building more prisons and expanding police powers, and a justification for involvement in foreign wars. These policies can be viewed less as mistaken efforts on the part of persons whose primary interest is public and individual health than as ways of maintaining existing social policies and social structures. 27 references