The study will test two behavioral intervention components to identify the combination of the two components that best supports people who inject drugs to achieve and sustain HIV viral load suppression. The study design is a 2-to-the-2 factorial experiment. The 2 represents the level of each component: 0 (receive) or 1 (don't receive). The 2 represents the number of components being tested. The four components are: 1) receiving (or not receiving) peer support services for medication-assisted treatment (MAT) uptake and persistence and 2) behavioral activation therapy for depression (BAT). Therefore, in order to test which combination of components produce the best outcome, this factorial design randomizes people to 1 of 4 conditions. Each condition represents a possible combination of the 2 components above. All participants will receive patient navigation for care engagement.
Inclusion Criteria: * be at least 18 years of age * be able to provide informed consent * be eligible to receive free HIV care services in Mexico * be HIV positive * have injected drugs in the last 30 days * not be on methadone replacement therapy * be willing to discuss MAT uptake with a peer * sign a medical release form to have medical data abstracted * agree to submit and describe locator information * agree to return to follow-up visits * able to communicate in Spanish * screen positive for depression on the PHQ-2 * have no plans of moving outside the study area in the next 12-months * meet one of the following: 1. not currently in possession of ART or not taking ART but prescribed ART or 2. sub-optimal ART adherence as at least one 4-day treatment interruption in the past 90 days or 3. sub-optimal retention in HIV care - never engaged or disengaged from HIV care as 2 or more missed clinic appointments in the last 9 months or 4. no viral load test done in the past six months or 5. self-reports a detectable viral load within the past 6 months Exclusion Criteria: * has not injected drugs in the last 30 days or do not have a verifiable opioid use disorder * is not HIV positive * is receiving methadone * is unwilling to discuss methadone uptake with a peer * does not screen positive for depression * is not able to provide informed consent * does not speak Spanish * has plans to move out of the city * does not qualify to receive free HIV care services in Mexico * has an appearance of psychological disturbance or severe cognitive impairment that could limit understanding of study procedures as determined by study staff