Private foundations can play a critical, catalytic role in changing American public education for the better, but they could and should be getting more bang for their bucks than they are right now. This article reports on a diverse collection of research papers that aims to shed unprecedented light both on the scope of contemporary education philanthropy and its impact on the field. The papers draw different and sometimes contradictory conclusions from the often-sketchy data available on what the scholars estimate is the roughly $1.5 billion a year that private giving supplies to K-12 education. The wide-ranging papers include new research on spending by the 30 biggest donors to K-12 education, the educational views of foundations' program officers, and the role of philanthropy in promoting school choice. One paper examines philanthropy's role in spurring changes in three school districts: Charlotte-Mecklenburg, North Carolina; Houston; and San Diego. Another looks at how private giving seeded Teach For America and the National Board for Professional Teaching Standards. Others examine philanthropy's impact on spreading new approaches, such as charter schools, vouchers, and small schools. Several scholars stress that donors could avoid wasting their resources by thinking harder about how best to complement the much larger sums flowing into education from public coffers. That shortcoming, they argue, has far-reaching ramifications.