Substance use treatment; Treatment for co-occurring substance use plus either serious mental health illness in adults/serious emotional disturbance in children; Outpatient; Outpatient day treatment or partial hospitalization; Intensive outpatient treatment; Regular outpatient treatment; Other contracted prescribing entity; Accepts clients using medication assisted treatment for alcohol use disorder but prescribed elsewhere; Other contracted prescribing entity; Accepts clients using MAT but prescribed elsewhere; Brief intervention; Cognitive behavioral therapy; Motivational interviewing; Relapse prevention; Substance use disorder counseling; Trauma-related counseling; Telemedicine/telehealth therapy; Private for-profit organization; State Substance use treatment agency; The Joint Commission; Federal military insurance (e.g., TRICARE); Private health insurance; Cash or self-payment; Adolescents; Clients with co-occurring mental and substance use disorders; Comprehensive mental health assessment; Comprehensive substance use assessment; Interim services for clients; Complete medical history/physical exam; Screening for tobacco use; Screening for substance use; Screening for mental disorders; Breathalyzer or blood alcohol testing; Drug and alcohol oral fluid testing; Aftercare/continuing care; Discharge Planning; Outcome follow-up after discharge; Employment counseling or training; Substance use disorder education; Smoking/vaping/tobacco cessation counseling; Individual counseling; Group counseling; Family counseling; Smoking permitted in designated area; Children/adolescents; Female; Male; Vaping permitted in designated area; Case management service; Mental health services; Suicide prevention services