One of the conventional justifications for the existence of large private philanthropic foundations in the United States has been their role as creative, innovative promoters of social change. Built on the fortunes of such industrial entrepreneurs as Andrew Carnegie and John D. Rockefeller, foundations early in this century were granted extensive legal privileges and immunity from government regulation in exchange for “voluntary” charitable support of science, medicine, and education, which like religion, theoretically existed in a private, non-governmental domain. Until the emergence of the federal government after World War II as the chief source of funding, private foundations played a predominant part in fostering educational and scientific innovation. Foundation support for social and institutional change, however, was not without inherent problems. The educational program of John D. Rockefeller's General Education Board during the decade of the 1930's illustrates the extent of these problems.