Comparing Treatments for HIV-Infected Opioid Users in an Integrated Care Effectiveness Study (CHOICES) Scale-Up

Inclusion Criteria: * Participant is at least 18 years old * Participant has provided written informed consent and HIPAA for medical record abstraction * Participant meets Diagnostic and Statistical (DSM)-5 criteria for moderate or severe opioid use disorder * Willing to be randomized to antagonist-based therapy or TAU for treatment of opioid use disorder * Has an HIV viral RNA count of greater than 200 copies/ml (not clinically suppressed) * Willing to establish ongoing HIV care at the site if not already receiving ongoing care * If female, willing to take at least one evidence-based measure to avoid becoming pregnant Exclusion Criteria: * Participant has a serious medical, psychiatric, or substance use disorder that, in the opinion of the study physician, would make participation hazardous to the participant, compromise study findings, or prevent participant from completing the study. Examples include: * Acutely life-threatening medical illnesses (e.g., active opportunistic infection, uncompensated heart failure, end-stage liver disease, acute hepatitis and moderate to severe renal impairment) as assessed by medical history, review of symptoms, physical exam and/or laboratory assessments * Severe, inadequately treated mental health disorder (e.g., active psychosis, uncontrolled manic-depressive illness) as assessed by history and/or clinical interview * Suicidal or homicidal ideation requiring immediate attention * Participant has aspartate aminotransferase (AST) or alanine aminotransferase (ALT) liver enzymes greater than five times the upper limit of normal on screening phlebotomy * Participant has an international normalized ratio (INR) \> 1.5 or platelet count \<100k * Participant has a known allergy or sensitivity to naloxone, naltrexone, polyactide-co-glycolide, carboxymethylcellulose, or other components of the Vivitrol diluent * Anticipate undergoing surgery during study participation * Have chronic pain requiring ongoing pain management with opioid analgesics * If female, currently (at time of consent) pregnant or breastfeeding or planning on conceiving in the coming months * Body habitus that, in the judgment of the study physician, precludes safe intramuscular injection on XR-NTX (e.g., excess fat tissue over the buttocks) * Received methadone of buprenorphine maintenance therapy for treatment of opioid dependence in the 4 weeks prior to screening * Have taken an investigational drug in another study within 30 days of study consent * Have had treatment with XR-NTX for opioid or alcohol dependence in the 4 weeks prior to consent * Are currently in jail, prison or have a pending legal action which may prevent an individual from completing the study