Substance use treatment; Outpatient; Outpatient methadone/buprenorphine or naltrexone treatment; Methadone used in Treatment; Does not treat alcohol use disorder; Federally-certified Opioid Treatment Program; Methadone maintenance; Methadone maintenance for predetermined time; Methadone; Motivational interviewing; Relapse prevention; Substance use disorder counseling; Private for-profit organization; State Substance use treatment agency; State department of health; Commission on Accreditation of Rehabilitation Facilities (CARF); The Joint Commission; National Committee for Quality Assurance (NCQA); SAMHSA certification for opioid treatment program (OTP); Federal, or any government funding for substance use treatment programs; Medicare; Medicaid; Private health insurance; Cash or self-payment; Pregnant/postpartum women; Comprehensive substance use assessment; Outreach to persons in the community; Screening for substance use; Breathalyzer or blood alcohol testing; Drug and alcohol oral fluid testing; Drug or alcohol urine screening; TB screening; Testing for Hepatitis B (HBV); Testing for Hepatitis C (HCV); Aftercare/continuing care; Discharge Planning; Naloxone and overdose education; Outcome follow-up after discharge; Housing services; Assistance with obtaining social services; HIV or AIDS education, counseling, or support; Hepatitis education, counseling, or support; Substance use disorder education; Individual counseling; Smoking permitted in designated area; Adults; Young adults; Female; Male; Opioid use disorder clients only; Sign language services for the deaf and hard of hearing; Vaping permitted in designated area; Case management service; Transportation assistance