The proposed research primarily seeks to assess the effectiveness of monetary-based CM in engaging HIV-infected drug users in HAART programs. Drug users identified through outreach will be randomized in a 1:1 ratio to one of two arms; participants in one arm will be offered a monetary-based reinforcer to participate (n=150) and participants in the second arm will be offered no reinforcer (n=150). Participation involves reporting to the study site for formal study of eligibility screening, consisting of clinical evaluation, medical history and laboratory testing required to determine eligibility to receive HAART. Participants randomized to the reinforcer arm will receive gift cards at the completion of screening procedures.