This report presents results from the Mental Health Client-Level Data (MH-CLD) and Mental Health Treatment Episode Data Set (MH-TEDS) for individuals receiving mental health treatment services in 2015, as well as selected data collection trends for such individuals from 2012 to 2015. The report provides information on mental health diagnoses, mental health treatment services, and demographic and substance use characteristics of individuals in mental health treatment in facilities that reported to individual state administrative data systems. One chapter is also devoted to characteristics of admissions to and discharges from mental health treatment, which can feature the same individual on multiple occasions.