Thirty years ago, Merle Curti ventured that “philanthropy has been one of the major aspects of and keys to American social and cultural development.” It was an apt, challenging, and important observation that was not immediately heeded and has yet to be sufficiently pursued. With Curti's comment in mind, I should like to sketch the development of a politics that took shape in the United States in the early twentieth century, and then to explore a number of relationships between that politics and some of the early activities of one of the large, grant-making foundations established before the First World War—the Carnegie Corporation of New York. Although the argument I shall present derives from a close study of only one foundation, the history of the Carnegie Corporation crosses and even merges with the history of many other institutions, including other foundations, and is inseparable from ideas, national trends, and both national and international events that have touched American society generally. What is more, the size, the longevity, the broad scope, the effectiveness, and the concern for responsible philanthropy that have always characterized the Carnegie Corporation have made it a leader and even a model for many of its peers. To some degree at least, then, in considering relationships between Carnegie Corporation philanthropy and what I shall call the politics of knowledge, one is also considering the validity of Curti's “hypothetical” claim. One is asking, not only whether, but, more importantly, how philanthropic foundations have achieved the significance Curti attributed to them.