Deaf and hard of hearing (DHH) American Sign Language users experience significant mental health-related disparities compared with non-DHH English speakers. Yet there is little empirical evidence documenting this priority population's communication access in mental health and substance use treatment facilities. This study measured mental health and substance use treatment facilities' noncompliance to Section 1557 of the Affordable Care Act (ACA), which requires health care facilities receiving government funds to provide effective communication access, such as a sign language interpreter, to DHH patients. Using nationally representative data from the Substance Abuse and Mental Health Services Administration, we found that 41 percent of mental health facilities and 59 percent of substance use treatment facilities receiving public funds reported not providing services in sign language in 2019 and were thus noncompliant with the ACA's mandate to provide accessible communication to DHH patients. We mapped these data to display state-level noncompliance, and we make detailed recommendations at the policy, facility, and provider levels. These include monitoring noncompliance among government-funded facilities, expanding state-by-state mental health licensure reciprocity and telehealth policies to improve access to American Sign Language-fluent mental health professionals and addiction counselors, establishing systematic processes to collect information on disability-related accommodation needs, and increasing the workforce of DHH American Sign Language-fluent providers.