Substance use treatment; Outpatient; Outpatient methadone/buprenorphine or naltrexone treatment; Regular outpatient 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; Brief intervention; Cognitive behavioral therapy; Contingency management/motivational incentives; Motivational interviewing; Relapse prevention; Substance use disorder counseling; Telemedicine/telehealth therapy; Trauma-related counseling; Private for-profit organization; State Substance use treatment agency; State department of health; Commission on Accreditation of Rehabilitation Facilities (CARF); SAMHSA certification for opioid treatment program (OTP); Drug Enforcement Agency (DEA); Cash or self-payment; Comprehensive substance use assessment; Outreach to persons in the community; Complete medical history/physical exam; Screening for tobacco use; Screening for substance use; Drug or alcohol urine screening; TB screening; Aftercare/continuing care; Discharge Planning; Naloxone and overdose education; Outcome follow-up after discharge; Housing services; Assistance with obtaining social services; Opioids detoxification; HIV or AIDS education, counseling, or support; Hepatitis education, counseling, or support; Health education services other than HIV/AIDS or hepatitis; Substance use disorder education; Individual counseling; Smoking not permitted; Adults; Young adults; Female; Male; Opioid use disorder clients only; Vaping not permitted; Case management service; Early intervention for HIV; Social skills development