Substance use treatment; Outpatient; Outpatient methadone/buprenorphine or naltrexone treatment; Regular outpatient treatment; Methadone used in Treatment; Does not treat alcohol use disorder; Federally-certified Opioid Treatment Program; Methadone maintenance; Methadone maintenance for predetermined time; Methadone; Relapse prevention; Substance use disorder counseling; Private for-profit organization; Commission on Accreditation of Rehabilitation Facilities (CARF); SAMHSA certification for opioid treatment program (OTP); Drug Enforcement Agency (DEA); Medicare; Medicaid; Private health insurance; Cash or self-payment; Comprehensive substance use assessment; Outreach to persons in the community; Screening for substance use; Screening for mental disorders; Breathalyzer or blood alcohol testing; Drug and alcohol oral fluid testing; Drug or alcohol urine screening; TB screening; Testing for Hepatitis C (HCV); Discharge Planning; Naloxone and overdose education; Outcome follow-up after discharge; Housing services; Assistance with obtaining social services; Health education services other than HIV/AIDS or hepatitis; Substance use disorder education; Individual counseling; Smoking permitted without restriction; Adults; Young adults; Female; Male; Opioid use disorder clients only; Vaping permitted without restriction; Case management service; Transportation assistance