In partnership with the Postsecondary Value Commission, we conducted a thought experiment on the costs of inequality in the US education system. Our simulation found that the US economy misses out on $956 billion dollars per year, along with numerous nonmonetary benefits, as a result of postsecondary attainment gaps by economic status and race/ethnicity. "The Cost of Economic and Racial Injustice in Postsecondary Education" finds that closing these gaps would require an initial public investment of at least $3.97 trillion, but the benefits would outweigh the costs over time. Equalizing educational attainment without increasing student debt for low-income adults could also boost GDP by a total of $764 billion annually. [During the writing of this report, Kathryn Peltier Campbell, Ban Cheah, Megan L. Fasules, Artem Gulish, Michael C. Quinn, Jenna R. Sablan, Nicole Smith, and Jeff Strohl received funding from the Institute for Higher Education Policy for work done on behalf of the Bill & Melinda Gates Foundation.]