Abstract-This study presents an evaluation of the effectiveness of the AIDS Community-Based Outreach/Intervention projects implemented as part of the National Institute on Drug Abuse (NIDA) Cooperative Agreement (CA), which began in 1990 and is currently ongoing. Participants in the CA were randomly assigned to one of two interventions: a NIDA/CA-developed standard intervention (SI); or the SI plus a site-specific enhanced intervention (EI). Analyses of drug use and needle-related risk behaviors were conducted among injection drug users (IDUs) in eight participating cities where follow-up rates of at least 60% were obtained (N=3,743). Results indicated that IDUs significantly reduced their needle-related risk behaviors following delivery of the interventions and that a substantial portion entered substance abuse treatment. However, there was relatively little to support the effectiveness of more expensive and involved enhanced interventions. A number of factors associated with increasing or maintaining high risk behaviors, including an HIV negative serostatus and a greater perceived chance of acquiring AIDS, were also observed. Continued outreach to drug injectors is recommended, as well as the development of new and creative interventions targeting individuals who are HIV negative and those who are aware of their high risk status but have not changed their behaviors in response to risk-reduction interventions.