Substance use treatment; Treatment for co-occurring substance use plus either serious mental health illness in adults/serious emotional disturbance in children; Outpatient; Regular outpatient treatment; Naltrexone used in Treatment; No formal relationship with prescribing entity; Accepts clients using medication assisted treatment for alcohol use disorder but prescribed elsewhere; No formal relationship with prescribing entity; Accepts clients using MAT but prescribed elsewhere; Naltrexone (extended-release, injectable); Medication for mental disorders; Brief intervention; Cognitive behavioral therapy; Motivational interviewing; Substance use disorder counseling; Trauma-related counseling; Telemedicine/telehealth therapy; Private non-profit organization; State Substance use treatment agency; State mental health department; Commission on Accreditation of Rehabilitation Facilities (CARF); Medicare; Medicaid; Federal military insurance (e.g., TRICARE); Private health insurance; Cash or self-payment; State-financed health insurance plan other than Medicaid; Clients with co-occurring mental and substance use disorders; Comprehensive mental health assessment; Comprehensive substance use assessment; Screening for tobacco use; Screening for substance use; Screening for mental disorders; Drug or alcohol urine screening; Metabolic syndrome monitoring; Discharge Planning; Outcome follow-up after discharge; Housing services; Assistance with obtaining social services; Health education services other than HIV/AIDS or hepatitis; Substance use disorder education; Smoking/vaping/tobacco cessation counseling; Individual counseling; Group counseling; Family counseling; Smoking not permitted; Children/adolescents; Female; Male; Sign language services for the deaf and hard of hearing; Other languages (excluding Spanish); Farsi; Vaping not permitted; Case management service; Mental health services; Suicide prevention services