Every year, 1 in 3 of the 2 million people with opioid use disorder in the United States is arrested.1 It follows that correctional facilities, that is, detention centers, jails, and prisons, have important roles in engaging people with opioid use disorder in effective treatment. Opioid agonist therapy with methadone hydrochloride, a full opioid agonist, or buprenorphine hydrochloride, a partial agonist, effectively treats opioid use disorder and reduces mortality.2 There is no comparable evidence for reduced mortality with naltrexone hydrochloride, an extended-release, full opioid antagonist also approved by the US Food and Drug Administration for treatment of opioid use disorder. Yet opioid agonist treatment is used infrequently in correctional facilities.3 What steps must be taken to change the situation?