Two years ago, we published a list of the 15 most powerful women in U.S. philanthropy. The idea for that article emerged because we were struck by how many women are involved in philanthropy at a high level—and equally struck by how little attention they tend to receive. In particular, while the spouses of billionaires often play a lead role in charting a couple’s giving, the spotlight usually falls on their better-known husbands when major gifts are made. Not only is this unfair, but it misses the real story of how today’s big philanthropy is unfolding as new mega-donors enter the scene—with women in the lead.