PROJECT SUMMARY/ABSTRACT In response to PAR-18-747, Addressing the Challenges of the Opioid Epidemic in Minority Health and Health Disparities Research in the U.S. (R01), this study seeks to determine the role of culturally competent strategies, and in particular workforce diversity, to improve treatment access, engagement, and medication- assisted treatment (MAT) maintenance dosage, i.e., methadone, buprenorphine and naltrexone for African- American and Hispanic populations in opioid treatment programs (OTP) nationwide. The study will rely on the National Drug Abuse Treatment System Survey (NDATSS), which is a unique, nationally representative longitudinal data (2005-2017); the study also will collect two waves of new data in 2021 and 2023 to assess the effect of culturally and linguistically appropriate services (CLAS) on OTP process measures [wait time, retention, and adequate MAT dosages). The study seeks to improve measurement of cultural competence using a gold standard instrument - the Cultural Competency Organizational Assessment (COA360 [CLAS]) and assess its predictive validity on process measures in 2021 and 2023. Findings will inform treatment programs’ use of cultural competency strategies to improve OTP wait time, retention and adequate dosage, and with these efforts reduce racial/ethnic disparities in opioid use disorder treatment. Policy-makers will be able to make decisions about how to allocate scarce resources needed to address the opioid epidemic.