Substance use treatment; Outpatient; Outpatient methadone/buprenorphine or naltrexone treatment; Methadone used in Treatment; Buprenorphine used in Treatment; Does not treat alcohol use disorder; Buprenorphine maintenance; Buprenorphine maintenance for predetermined time; Federally-certified Opioid Treatment Program; Methadone maintenance; Methadone maintenance for predetermined time; Methadone; Buprenorphine without naloxone; Cognitive behavioral therapy; Motivational interviewing; Matrix Model; Relapse prevention; Substance use disorder counseling; Private for-profit organization; State Substance use treatment agency; Commission on Accreditation of Rehabilitation Facilities (CARF); SAMHSA certification for opioid treatment program (OTP); Drug Enforcement Agency (DEA); IHS/Tribal/Urban (ITU) funds; Medicare; Medicaid; Federal military insurance (e.g., TRICARE); Private health insurance; Cash or self-payment; Pregnant/postpartum women; Screening for substance use; Breathalyzer or blood alcohol testing; Drug and alcohol oral fluid testing; Drug or alcohol urine screening; TB screening; Discharge Planning; Naloxone and overdose education; Outcome follow-up after discharge; Housing services; Assistance with obtaining social services; Substance use disorder education; Individual counseling; Group counseling; Smoking not permitted; Adults; Young adults; Female; Male; Opioid use disorder clients only; Vaping not permitted; Case management service