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 use MAT for opioid use disorders; Private for-profit organization; State Substance use treatment agency; Federally Qualified Health Center; Cash or self-payment; Sliding fee scale (fee is based on income and other factors); Adolescents; Young adults; Adult women; Adult men; Seniors or older adults; Lesbian, gay, bisexual, transgender, or queer/questioning (LGBTQ); Veterans; Active duty military; Criminal justice (other than DUI/DWI)/Forensic clients; Clients with co-occurring mental and substance use disorders; Clients who have experienced sexual abuse; Clients who have experienced trauma; Comprehensive substance use assessment; Interim services for clients; Screening for substance use; Professional interventionist/educational consultant; Breathalyzer or blood alcohol testing; Drug and alcohol oral fluid testing; Drug or alcohol urine screening; Aftercare/continuing care; Discharge Planning; Outcome follow-up after discharge; HIV or AIDS education, counseling, or support; Hepatitis education, counseling, or support; Substance use disorder education; Individual counseling; Group counseling; Family counseling; Marital/couples counseling; Smoking permitted without restriction; Children/adolescents; Seniors; Female; Male; Specially designed program for DUI/DWI clients