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; Does not use medication assisted treatment for alcohol use disorder; Does not use MAT for opioid use disorders; Brief intervention; Cognitive behavioral therapy; Contingency management/motivational incentives; Matrix Model; Relapse prevention; Substance use disorder counseling; Telemedicine/telehealth therapy; Private for-profit organization; State Substance use treatment agency; State mental health department; State department of health; Commission on Accreditation of Rehabilitation Facilities (CARF); Medicare; Medicaid; 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; Comprehensive substance use assessment; Screening for substance use; Screening for mental disorders; Drug or alcohol urine screening; Discharge Planning; Outcome follow-up after discharge; Self-help groups; Assistance with obtaining social services; Mentoring/peer support; 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; Social skills development; Transportation assistance