Substance use treatment; Treatment for co-occurring substance use plus either serious mental health illness in adults/serious emotional disturbance in children; Outpatient; Intensive outpatient treatment; Outpatient methadone/buprenorphine or naltrexone 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; Prescribes naltrexone; Relapse prevention with naltrexone; Accepts clients using MAT but prescribed elsewhere; 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); Federal, or any government funding for substance use treatment programs; 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; Clients who have experienced trauma; 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; Aftercare/continuing care; Discharge Planning; Outcome follow-up after discharge; Substance use disorder education; Group counseling; Smoking permitted in designated area; Adults; Young adults; Female; Male; Sign language services for the deaf and hard of hearing; Vaping permitted in designated area; Suicide prevention services