This study adds a quasi-control arm to JCOIN 034, a clinical trial comparing extended release naltrexone (XR-NTX) to extended release buprenorphine (Brixadi formulation, XR-B) initiated prior to release from jail. In this quasi-control arm, additional data will be collected from 120 incarcerated men and women receiving sublingual buprenorphine (SL-B) in jail, who will continue their buprenorphine treatment in the community post-release, and complete follow up assessments over 12 months (treatment occurs in months 1-7; month 12 is follow up data collection only). This quasi-control arm will be compared to participants randomized to XR-B in the parent study. Propensity scores will be used to permit causal modeling by way of propensity score weighted generalized linear mixed models. HEAL JCOIN common measures will be utilized to facilitate data harmonization and cross-study analyses. We plan to conduct semi-structured interviews with correctional administrators, correctional officers; and jail health providers (N=25) to understand issues regarding barriers to facilitating SL-B implementation. The study has three specific aims: Aim 1: To determine the effectiveness of XR-B (Brixadi) compared to SL-B in terms of (a) pharmacotherapy adherence (days in buprenorphine treatment), b) illicit opioid urine test results; (c) self-reported illicit opioid use; (d) overdose events (non-fatal and fatal); (e) quality of life (i. physical health; ii. mental health); (f) HIV risk behaviors (i. sexual behavior; ii. needle use or sharing); and (g) criminal activity (i. crime days; ii. re-arrest; iii. re-incarceration). Aim 2: Explore barriers and facilitators to SL-B implementation in jail: (1) dose induction; (2) diversion and procedures for reducing diversion; (3) continuity of care after release or transfer to another facility; (4) staffing (both custody and medical) needs for daily buprenorphine dosing; and (5) the process of verifying the dosage of an individual coming from a community maintenance program after being arrested. Aim 3: To (a) calculate the cost to the correctional health system of implementing and sustaining an SL-B or XR-B program; and (b) determine the relative value of XR-B compared to SL-B, including the subsequent community treatment costs, from a state-policymaker and societal perspective.