Research on disparities in opioid use disorder (OUD) treatment has revealed a deeply segregated landscape of medication access. Measuring area-based segregation is a promising tool to dissect how racialized structural disadvantage may intersect with access to OUD treatment. In my research, I use national insurance claims to study the real-world comparative effectiveness of buprenorphine and methadone in pregnant people with opioid use disorder in the United States, with a focus on populations underrepresented in clinical trials. Together with Drs. Ebony Carter and Richard Grucza, I am working to enrich insurance claims with area-based measures of segregation via zip codes in order to better understand how segregation impacts the real-world effectiveness of “gold standard” addiction treatments.