The aim of this report was to estimate the effect on commercial health insurance premium rates of non-discriminatory coverage for treating people who have serious mental illness. The Equitable Health Care for Severe Mental Illness Act — S.298 — would require services for treatment of serious mental illness in a manner that: (1) is not more restrictive than coverage provided for other major physical illnesses;(2) provides adequate financial protection to the person requiring the medical treatment for a person who has severe mental illness; and(3) is consistent with effective and common methods of controlling health care costs for other major physical illness. The authors conclude that S.298 could increase total plan premiums by 2.5%.