Despite advances in HIV treatment, HIV-infected drug users continue to have poor treatment outcomes. With suboptimal HIV treatment and poorly controlled HIV infection, drug users have great potential to transmit HIV infection to their partners, leading to serious public health consequences. Few studies test interventions to improve outcomes among HIV-infected drug users, and many focus on improving HAART adherence. In active drug users, these interventions, which improve adherence but do not affect drug use, lead to modest, if any, improvement in viral load (VL) suppression. In drug users, achieving and maintaining clinically significant VL suppression without addressing drug use is unlikely. Despite this, we are not aware of any study that has examined whether an intervention that aims to reduce drug use improves HIV-related outcomes. Because abstinence-reinforcing contingency management (CM) overwhelmingly reduces drug use, and reduction in drug use is associated with improved HIV outcomes, the benefits of abstinence-reinforcing CM are likely to extend to improving HIV treatment outcomes. However, this has not been studied. Our study will be among the first to test whether CM that reinforces one behavior (achieving abstinence) leads to improved outcomes in other related behaviors (achieving VL suppression). We propose to test whether an abstinence-reinforcing CM intervention improves VL suppression in HIV-infected drug users. We will enroll 202 participants with suboptimal drug and HIV treatment (using cocaine or opioids while receiving opioid agonist treatment, with detectable VL while prescribed HAART) to test a 16-week intervention of abstinence-reinforcing CM on VL suppression. Participants will be randomized to the abstinence-reinforcing CM intervention or performance feedback (control condition). The CM group can earn $1320 based on drug-free urine. Participants will be followed for 28 weeks, and data sources will include blood and urine tests, questionnaires, and pill counts. The primary outcome will be change in VL, and secondary outcomes include CD4 count, abstinence, and HAART adherence. Our study aims are to: 1) test the efficacy of a 16-week abstinence-reinforcing contingency management intervention on VL suppression, and 2) examine mechanisms of achieving VL suppression with our abstinence-reinforcing CM intervention. We hypothesize that those randomized to the CM (vs. control) group will have greater VL suppression, and that the CM group will have greater abstinence, leading to higher adherence, leading to greater VL suppression. Our proposal is innovative and responsive to RFA DA-11-001. It is well-established that abstinence-reinforcing CM reduces drug use, and reduction in drug use is associated with improvements in HIV treatment. What is not known, and what this study will elucidate, is whether abstinence-reinforcing CM is efficacious in improving VL suppression, and the mechanisms underlying this effect. Given the central role that CM is now playing in large public health trials, our findings will have substantial public health implications.