Methadone is a Food and Drug Administration- (FDA-) approved medication for treating opioid use disorder (OUD), a chronic brain disease that affects more than 2.7 million people in the United States aged 12 and older. Despite its effectiveness in saving lives, many barriers impede access to, initiation of, and retention in methadone treatment for OUD. To address these barriers, on March 3 and 4, 2022, the National Academies of Sciences, Engineering, and Medicine hosted a workshop on "Methadone Treatment for Opioid Use Disorder: Examining Federal Regulations and Laws," at the request of the Office of National Drug Control Policy in the Executive Office of the President. This publication summarizes the presentation and discussion of the workshop.Table of ContentsFront Matter1 Introduction and Background2 Methadone Treatment: Personal Perspectives3 The History of Methadone and Barriers to Access for Different Populations4 Current Federal Priorities and Regulatory Flexibilities during the COVID-19 Pandemic5 Improving Access to Quality Treatment in Opioid Treatment Programs through Regulatory Innovation6 Improving Access to Quality Treatment in the Criminal Justice System and Other Institutional Settings7 Expanding Access to Methadone through Regulatory Innovation: Envisioning Approaches Outside the Opioid Treatment Program System8 Ensuring Equitable Access to Methadone by Removing Current Barriers and Providing Incentives9 Frameworks to Guide the Assessment of Legal and Regulatory Challenges10 Moving Forward: Potential Concrete Legal and Regulatory ActionsAppendix A: ReferencesAppendix B: Workshop AgendaAppendix C: Commissioned Papers