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; Regular outpatient treatment; General Hospital (including VA hospital); Does not treat alcohol use disorder; Does not treat opioid use disorders; Anger management; Cognitive behavioral therapy; Dialectical behavior therapy; Relapse prevention; Substance use disorder counseling; 12-step facilitation; Private non-profit organization; State mental health department; State department of health; The Joint Commission; Medicare; Medicaid; Federal military insurance (e.g., TRICARE); Private health insurance; Cash or self-payment; State-financed health insurance plan other than Medicaid; Adult women; Adult men; Seniors or older adults; Clients with co-occurring mental and substance use disorders; Comprehensive mental health assessment; Screening for substance use; Screening for mental disorders; Drug or alcohol urine screening; Aftercare/continuing care; Discharge Planning; Self-help groups; Mentoring/peer support; Substance use disorder education; Group counseling; Family counseling; Smoking not permitted; Children/adolescents; Seniors; Female; Male; Mental health services; Social skills development