Objectives. To document state Medicaid pre- and postrelease initiatives for individuals in the criminal legal system with substance use disorder (SUD). Methods. An Internet-based survey was sent in 2021 to Medicaid directors in all 50 US states and the District of Columbia to determine whether they were pursuing initiatives for persons with SUD across 3 criminal legal settings: jails, prisons, and community corrections. A 90% response rate was obtained. Results. In 2021, the majority of states did not report any targeted Medicaid initiatives for persons with SUD residing in criminal legal settings. Eighteen states and the District of Columbia adopted at least 1 Medicaid initiative for persons with SUD across the 3 criminal legal settings. The most commonly adopted initiatives were in the areas of medication for opioid use disorder treatment and Medicaid enrollment. Out of 24 possible initiatives for each state (8 initiatives across 3 criminal legal settings), the 2 most commonly adopted were (1) provision of medication treatment of opioid use disorder before release from criminal legal settings (16 states) and (2) facilitation of Medicaid enrollment through suspension rather than termination of Medicaid enrollment upon entry to a criminal legal setting (14 states). Initiatives pertaining to Medicaid SUD care coordination were adopted by the fewest (9) states. Conclusions. In 2021, states' involvement in Medicaid SUD initiatives for criminal legal populations remained low. Increased adoption of Medicaid SUD initiatives across criminal legal settings is needed, especially knowing the high rate of overdose mortality among this group. (Am J Public Health. 2024;114(5):527-530. https://doi.org/10.2105/AJPH.2024.307604).