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; Cognitive behavioral therapy; Motivational interviewing; Substance use disorder counseling; Trauma-related counseling; 12-step facilitation; Private non-profit organization; State Substance use treatment agency; State department of health; Federal, or any government funding for substance use treatment programs; No payment accepted; Payment assistance (check with facility for details); Seniors or older adults; Clients with co-occurring mental and substance use disorders; Comprehensive mental health assessment; Comprehensive substance use assessment; Outreach to persons in the community; Screening for tobacco use; Screening for substance use; Screening for mental disorders; Aftercare/continuing care; Outcome follow-up after discharge; Self-help groups; Housing services; Assistance with obtaining social services; Recovery coach; Mentoring/peer support; Health education services other than HIV/AIDS or hepatitis; Substance use disorder education; Smoking/vaping/tobacco cessation counseling; Individual counseling; Group counseling; Smoking not permitted; Adults; Seniors; Female; Male; Vaping not permitted; Case management service; Mental health services; Social skills development