Mental illness imposes a substantial burden on individuals and society. Using data from national surveys and a newly developed methodology for calculating costs, the authors estimate that in 1985 the total economic costs of mental illness were $103.7 billion. Of this total, direct treatment and support. costs were $42.5 billion, or 11.5 percent of total personal health care spending for all illnesses. Morbidity costs-the value of reduced or lost productivity-amounted to $47.4 billion. Mortality costs-the lost value of productivity due to premature death resulting from mental illness- were estimated to be $9.3 billion, or 5.1 percent of total productivity losses for all deaths. Other related costs, including the cost of caregiver services, amounted to $4.5 billion.