Abstract The proposed study consists of adding a quasi-control arm to the parent study wherein 120 incarcerated men and women receiving sublingual buprenorphine (SL-B) in jail will be asked to participate by continuing their buprenorphine treatment in the community and completing follow- up assessments over 12 months post-release (treatment occurs months 1-7, 12-month follow- up only). This quasi-control arm will be compared to participants randomized to BRIXADI (extended-release buprenorphine, 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. We plan to use the jails that are currently participating in our HEAL JCOIN R01 that are already providing SL-B and part of the initial cohort of Bill-116. The study has three specific aims: Aim 1. To determine the effectiveness of XR-B 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 (XR-B costs are being calculated in parent trial but will need to be estimated for new sites); 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. The study will be highly significant because most individuals with OUD do not receive buprenorphine treatment while in jail, thereby substantially raising their likelihood of relapse to drug use, overdose death, and re-incarceration. Finally, it is important to understand how differing treatment modalities (monthly extended- release injections vs. daily oral doses) and their real-world implementations affect pharmacotherapy adherence and opioid related harms.