ImportanceExpanding the use of buprenorphine for treating opioid use disorder is a critical component of the US response to the opioid crisis, but few studies have examined how state policies are associated with buprenorphine dispensing.ObjectiveTo examine the association of 6 selected state policies with the rate of individuals receiving buprenorphine per 1000 county residents.Design, Setting, and ParticipantsThis cross-sectional study used 2006 to 2018 US retail pharmacy claims data for individuals dispensed buprenorphine formulations indicated for treating opioid use disorder.ExposuresState implementation of policies requiring additional education for buprenorphine prescribers beyond waiver training, continuing medical education related to substance misuse and addiction, Medicaid coverage of buprenorphine, Medicaid expansion, mandatory prescriber use of prescription drug monitoring programs, and pain management clinic laws were examined.Main Outcomes and MeasuresThe main outcome was buprenorphine treatment months per 1000 county residents as measured using multivariable longitudinal models. Statistical analyses were conducted from September 1, 2021, through April 30, 2022, with revised analyses conducted through February 28, 2023.ResultsThe mean (SD) number of months of buprenorphine treatment per 1000 persons nationally increased steadily from 1.47 (0.04) in 2006 to 22.80 (0.55) in 2018. Requiring that buprenorphine prescribers receive additional education beyond that required to obtain the federal X-waiver was associated with significant increases in the number of months of buprenorphine treatment per 1000 population in the 5 years following implementation of the requirement (from 8.51 [95% CI, 2.36-14.64] months in year 1 to 14.43 [95% CI, 2.61-26.26] months in year 5). Requiring continuing medical education for physician licensure related to substance misuse or addiction was associated with significant increases in buprenorphine treatment per 1000 population in each of the 5 years following policy implementation (from 7.01 [95% CI, 3.17-10.86] months in the first year to 11.43 [95% CI, 0.61-22.25] months in the fifth year). None of the other policies examined was associated with a significant change in buprenorphine months of treatment per 1000 county residents.Conclusions and RelevanceIn this cross-sectional study of US pharmacy claims, state-mandated educational requirements beyond the initial training required to prescribe buprenorphine were associated with increased buprenorphine use over time. The findings suggest requiring education for buprenorphine prescribers and training in substance use disorder treatment for all controlled substance prescribers as an actionable proposal for increasing buprenorphine use, ultimately serving more patients. No single policy lever can ensure adequate buprenorphine supply; however, policy maker attention to the benefits of enhancing clinician education and knowledge may help to expand buprenorphine access.