Indiana University-Purdue University Indianapolis (IUPUI) / The United States is experiencing a severe opioid use epidemic with more than 2 million people currently suffering from opioid use disorder (OUD), of which, over 1 million need treatment. Opioid treatment programs (OTPs) are evidence-based modality providing comprehensive care to individuals experiencing OUD. OTPs provide counseling, medical assessments, and medication-assisted treatment, which decrease the use of illicit opioids, reduce associated deaths, criminality, and improve the psychosocial wellbeing of its patients. However, OTPs have been extensively regulated at the federal, state, and local levels with little consistency and varying degrees of enforcement across the country, particularly at the state level, creating a “regulatory fog”. This complex regulatory environment has made it challenging to study new or changing regulations and their impact on health outcomes. In order to better understand the variation of OTP regulation, this dissertation: (1) employs public health law research methods to map the entire landscape of state-level regulation of OTPs and associated state characteristics in effect on January 1, 2017; (2) examine how state-level regulations affect the delivery of care from the perspective of OTP administrators through key-information interviews; and (3) examines associations between regulatory burden and related health outcomes of individuals experiencing OUD, by state.