Public education funding relies on revenues from a variety of sources, from local taxpayers to federal programs targeting students with specific needs. The vast sum of funding collected--in excess of $600 billion annually--often masks which entities fund the education of our nation's youth. Questions of funding adequacy and equity across school sectors, school districts and individual schools are prominent in discussions of how to improve educational outcomes, especially for students from disadvantaged backgrounds. This report is a follow-up to a 2014 report which analyzed the non-public revenue received by public charter schools and traditional public schools (TPS) in the 15 states with both substantial charter school sectors and reliable data regarding the specific sources of non-public revenue. Findings reveal that both TPS and charters receive the lion's share of their revenue from public sources--further evidence that they are merely two different governance structures for public schools. At the same time, both TPS and charters are involved in the private-sector economy by selling meals to their students, reaping profits from their investments of reserve funds and competing for charitable funds. Although some charter school networks and individual schools receive non-public revenue that covers 10-15% of the per-pupil cost of education at their schools, no charter schools are more dependent on private funds than they are on public funds and more than a third of charter schools receive no revenue at all from private philanthropy. The findings of the study reveal that private philanthropy alone cannot be relied upon to close the charter school funding gap in the U.S. Therefore, if children in public charter schools are to receive funding levels that are equitable to their peers in TPS, significant changes will have to be made in the public school funding laws in many states. [To view the 2014 report, "Charter School Funding: Inequity Expands," see ED581409.]