Substance use treatment; Treatment for co-occurring substance use plus either serious mental health illness in adults/serious emotional disturbance in children; Outpatient; Regular outpatient treatment; Does not treat alcohol use disorder; Does not treat opioid use disorders; Clonidine; Brief intervention; Cognitive behavioral therapy; Contingency management/motivational incentives; Dialectical behavior therapy; Motivational interviewing; Relapse prevention; Substance use disorder counseling; Trauma-related counseling; Private non-profit organization; State Substance use treatment agency; State mental health department; 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; Adolescents; Clients with co-occurring mental and substance use disorders; Comprehensive mental health assessment; Comprehensive substance use assessment; Interim services for clients; Outreach to persons in the community; Screening for tobacco use; Screening for substance use; Screening for mental disorders; Drug or alcohol urine screening; Aftercare/continuing care; Discharge Planning; Assistance with obtaining social services; Mentoring/peer support; Treatment for gambling disorder; Substance use disorder education; Smoking/vaping/tobacco cessation counseling; Individual counseling; Group counseling; Family counseling; Smoking permitted in designated area; Children/adolescents; Female; Male; Sign language services for the deaf and hard of hearing; Case management service; Mental health services; Social skills development