The issue of the prevention of AIDS among intravenous drug users (IDUs) is a serious issue that must be addressed. The large number of hard to reach IDUs that enter and are retained in the jail system make the jail an excellent place to provide HIV/AIDS prevention programs. Based on a successful jail-based prevention program, the Community Outreach Project on AIDS in Southern Arizona (COPASA), this article addresses six issues that HIV/AIDS educators need to deal with when providing HIV/AIDS prevention in a jail setting. These issues include (a) the constraints of the jail setting; (b) access to inmates; (c) the educational needs of IDUs; (d) type, format, and content of the intervention; (e) HIV/AIDS testing in the jail; and (f) evaluation of the effectiveness of HIV/AIDS jail-based programs.