Our analysis shows that $850 billion to $1 trillion a year of illicit money passes out of developing countries, through the shadow financial system, and into industrial countries. This is the most damaging economic condition hurting the global poor. G20 leaders need to refocus on changing the culture of opacity embodied in the global shadow financial system in order to curtail the flow of illicit money across borders. Several measures can achieve this end—automatic exchange of tax information, beneficial ownership, harmonizing predicate offenses, and country-by-country reporting.