Policy Definitions for "Serious Mental Illness" Across 56 United States, Districts and Territories

The construct "serious/severe mental illness," or "SMI," is a priority within mental health initiatives in the United States. However, there is a lack of clarity regarding its operational definition in policy and practice settings. This study involved an evaluation of "SMI" policy definitions across the 50 United States, five territories, and Washington, D.C. via review of public legislation, department of health (DOH) websites and contacts. Policy definitions were available for 46 (82.2%) locations. Of those definitions, 32 (69.6%) were listed within legislation and 18 (39.1%) used pre-existing organizational or agency definitions. Only nine (19.6%) definitions indicated they were intended to determine eligibility for specific mental health services. Most locations (N = 38; 82.6%) mentioned functional impairment or disability as an eligibility criterion and suggested any psychiatric diagnosis could be considered SMI (N = 34; 73.9%). Results indicate substantial variability in SMI policy definitions across geographic locations with implications for service eligibility, delivery, and receipt.