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; Brief intervention; Contingency management/motivational incentives; Motivational interviewing; Matrix Model; Substance use disorder counseling; Private for-profit organization; State Substance use treatment agency; State department of health; Commission on Accreditation of Rehabilitation Facilities (CARF); Federally Qualified Health Center; SAMHSA certification for opioid treatment program (OTP); Drug Enforcement Agency (DEA); Federal, or any government funding for substance use treatment programs; Medicare; Medicaid; Private health insurance; Cash or self-payment; Comprehensive substance use assessment; Outreach to persons in the community; Complete medical history/physical exam; 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; Assistance with obtaining social services; Hepatitis education, counseling, or support; Health education services other than HIV/AIDS or hepatitis; Substance use disorder education; Individual counseling; Smoking permitted in designated area; Adults; Young adults; Female; Male; Opioid use disorder clients only; Vaping permitted in designated area; Case management service; Social skills development; Transportation assistance