Adults; Young adults; Female; Male; Opioid use disorder clients only; Case management service; Early intervention for HIV; Mental health services; Social skills development; Transportation assistance; Integrated primary care services; Substance use treatment; Detoxification; Treatment for co-occurring substance use plus either serious mental health illness in adults/serious emotional disturbance in children; Outpatient; Outpatient detoxification; Intensive outpatient treatment; Outpatient methadone/buprenorphine or naltrexone treatment; Regular outpatient treatment; Methadone used in Treatment; Naltrexone used in Treatment; Does not use medication assisted treatment for alcohol use disorder; Federally-certified Opioid Treatment Program; Methadone maintenance; Prescribes naltrexone; Methadone; Naltrexone (extended-release, injectable); Private non-profit organization; State Substance use treatment agency; State mental health department; State department of health; Commission on Accreditation of Rehabilitation Facilities (CARF); Council on Accreditation (COA); Federally Qualified Health Center; Federal, or any government funding for substance use treatment programs; Medicare; Medicaid; Private health insurance; Cash or self-payment; State-financed health insurance plan other than Medicaid; Payment assistance (check with facility for details); Sliding fee scale (fee is based on income and other factors); Adult women; Adult men; Clients with co-occurring mental and substance use disorders; Clients with HIV or AIDS; Comprehensive mental health assessment; Comprehensive substance use assessment; Interim services for clients; Outreach to persons in the community; Screening for tobacco use; Screening for substance use; Screening for mental disorders; Professional interventionist/educational consultant; Breathalyzer or blood alcohol testing; Drug or alcohol urine screening; HIV testing; TB screening; Aftercare/continuing care; Discharge Planning; Naloxone and overdose education; Outcome follow-up after discharge; Self-help groups; Housing services; Assistance with obtaining social services; Mentoring/peer support; Treatment for gambling disorder; Medication routinely used during 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; Smoking/vaping/tobacco cessation counseling; Individual counseling; Group counseling; Family counseling; Hepatitis A (HAV) vaccination; Hepatitis B (HBV) vaccination; Smoking permitted in designated area