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; Does not treat alcohol use disorder; Does not treat opioid use disorders; Brief intervention; Cognitive behavioral therapy; Dialectical behavior therapy; Motivational interviewing; Relapse prevention; Substance use disorder counseling; 12-step facilitation; Private non-profit organization; Council on Accreditation (COA); Federal, or any government funding for substance use treatment programs; Cash or self-payment; Adolescents; Young adults; Adult women; Adult men; Seniors or older adults; Clients with co-occurring pain and substance use disorders; Aftercare/continuing care; Discharge Planning; Individual counseling; Group counseling; Family counseling; Marital/couples counseling; Smoking not permitted; Children/adolescents; Seniors; Female; Male; Spanish; Case management service; Domestic violence services, including family or partner; Mental health services