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; No formal relationship with prescribing entity; Does not treat alcohol use disorder; Accepts clients using MAT but prescribed elsewhere; Medication for mental disorders; Nicotine replacement; Non-nicotine smoking/tobacco cessation; Private non-profit organization; State mental health department; Federal, or any government funding for substance use treatment programs; Medicare; Medicaid; Cash or self-payment; Sliding fee scale (fee is based on income and other factors); Young adults; 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 and alcohol oral fluid testing; Drug or alcohol urine screening; Aftercare/continuing care; Discharge Planning; Assistance with obtaining social services; Mentoring/peer support; Employment counseling or training; Substance use disorder education; Smoking/vaping/tobacco cessation counseling; Individual counseling; Group counseling; Family counseling; Smoking not permitted; Adults; Young adults; Female; Male; Spanish; Sign language services for the deaf and hard of hearing; Vaping not permitted; Case management service; Mental health services; Social skills development; Suicide prevention services