Serious mental illness (SMI) is a disabling condition that develops early in life and imposes substantial economic burden. There is a growing belief that early intervention for SMI has lifelong benefits for patients. However, assessing the cost-effectiveness of early intervention efforts is hampered by a lack of evidence on the long-term benefits. We addressed this by using a dynamic microsimulation model to estimate the lifetime burden of SMI for those diagnosed by age twenty-five. We estimated that the per patient lifetime burden of SMI is $1.85 million. We also found that a policy intervention focused on improving the educational attainment of people with SMI reduces the average per person burden of SMI by $73,600 (4.0 percent)-a change driven primarily by higher lifetime earnings-or over $8.9 billion in reduced burden per cohort of SMI patients. These findings provide a benchmark for the potential value of improving educational attainment for people with SMI.