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; Regular outpatient treatment; Buprenorphine used in Treatment; Naltrexone used in Treatment; Does not treat alcohol use disorder; Buprenorphine maintenance; Prescribes buprenorphine; Prescribes naltrexone; Buprenorphine with naloxone; Naltrexone (oral); Medication for mental disorders; Cognitive behavioral therapy; Motivational interviewing; Matrix Model; Relapse prevention; Substance use disorder counseling; Telemedicine/telehealth therapy; Private non-profit organization; State Substance use treatment agency; State mental health department; 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; Sliding fee scale (fee is based on income and other factors); Adolescents; Clients with co-occurring mental and substance use disorders; Clients who have experienced trauma; Comprehensive mental health assessment; Comprehensive substance use assessment; Interim services for clients; Outreach to persons in the community; Screening for tobacco use; Drug and alcohol oral fluid testing; Drug or alcohol urine screening; Aftercare/continuing care; Discharge Planning; Outcome follow-up after discharge; Assistance with obtaining social services; Substance use disorder education; Smoking/vaping/tobacco cessation counseling; Individual counseling; Group counseling; Smoking permitted in designated area; Children/adolescents; Female; Male; Vaping permitted in designated area; Case management service; Mental health services