The investigators seek to develop an intensive intervention that incorporates the most effective techniques for promoting ART adherence in drug users, and deliver them in a manner that allows for their large-scale implementation as long-term or even permanent adjuncts to ART. The investigators propose a three year development project for an ART adherence intervention that bundles a targeted group of effective component interventions into a Smartphone application that is easy for patients to use, simple to manage, and maximally convenient for all stakeholders. Toward that end, the intervention to be developed under this project will (1) facilitate consultation with care providers (2) provide reminders when a dose is overdue, (3) provide remote electronic observation of medication-taking, and (4) provide incentives for ART adherence. The proposed intervention (SteadyRx) is highly innovative: no previous ART adherence intervention has involved direct observation of medication administration and contingency management, despite their respective effectiveness in isolation. Importantly, no mobile/remote intervention currently under development is as intensive as SteadyRx.