We now write because we are alarmed about a major new force that has entered the field of charitable giving. It has so far been hardly noticed by the general public. But now it is threatening to undermine the American system for funding charity. This force is the commercial “donor-advised fund,” the fastest-growing, but still largely unknown, charitable vehicle. Donor-advised funds (or DAFs) give donors all of the tax benefits of charitable giving while imposing no obligation that the money be put to active charitable use.