This study is an open label randomized controlled trial of extended-release buprenorphine (BRIXADI, XR-B) vs. sublingual buprenorphine (SL-B) in a large metropolitan jail. An open-label design will randomly assign 240 adults with moderate-to-severe OUDs who are soon-to-be-released from jail to either XR-B (n=120) or SL-B (n=120) treatment in jail followed by 6-months of post-release buprenorphine treatment, a 7-month safety visit, and a final long-term follow-up at 12-months.