IntroductionOpioid agonist treatment (OAT) is the only treatment for opioid use disorder (OUD) proven to reduce overdose mortality, yet access to this evidence-based treatment remains poor. The purpose of this cross-sectional audit study was to assess OAT availability at residential substance use services in North Carolina. MethodsWe conducted a state-wide inventory of residential substance use service providers in North Carolina and subsequently called all providers identified, posing as uninsured persons who use heroin, seeking treatment services. Program characteristics, as reported in phone calls, were systematically recorded. We used Fisher's exact tests to assess what program characteristics were associated with OAT availability and with staff making discouraging comments about OAT. We used unsupervised agglomerative clustering to identify facilities with similar characteristics. ResultsOf the 94 treatment providers identified, we successfully contacted and collected data from 66. Of those, only 7 (10.6 %) provide OAT on site; an additional 9 (13.6 %) allow OAT through an outside or community-based prescriber. Only 8 (12.1 %) providers were licensed to provide residential substance use treatment. Staff from 33 (50.0 %) providers made negative, discouraging, or stigmatizing remarks about OAT—for example, that OAT substitutes one addiction for another or does not constitute “true recovery.” OAT availability was positively associated with a provider holding a state license for any substance use-related service (41.9 % vs 8.6 %, p = 0.002) and offering 12-step programming (36.1 % vs. 10/0 %, p = 0.020). OAT availability was negatively associated with faith-based programming (6.1 % vs 42.4 %, p = 0.001), dress codes (5.3 % vs 50.0 %, p < 0.001), and mandates that residents work in a provider-owned and -operated commercial enterprise (5.0 % vs 32.6 %, p = 0.026). Cluster analysis revealed that the most common (n = 21) type of service provider in North Carolina is an unlicensed, faith-based organization that prohibits OAT, imposes a dress code, and mandates that residents work, often in provider-owned and -operated commercial enterprises. ConclusionEvidence-based treatments for OUD are largely unavailable at providers of residential substance use services in North Carolina. The prohibition of OAT occurs most often among providers who are unlicensed and impose labor and/or 12-step mandates on residents. Changes to state licensure requirements and exemptions may help improve OAT availability.