During the first two decades of radio broadcasting in the United States, commercial broadcasters persuaded federal regulators, much of the public, and many educators that there was little need for independent noncommercial stations. Educational programming could be entrusted to "cooperation" between commercial hosts and guest educators. An organization called the National Advisory Council in Education, backed by the Carnegie Corporation and the National Broadcasting Company, was particularly effective in promoting these ideas. The "cooperation" doctrine crucially undercut support for educational radio stations during the formative years of American broadcasting. Its wide acceptance helped reduce the number of independent educational broadcasters from 128 in 1925 to just 36 a decade later. This article reconsiders the origins of the public broadcasting system, underscoring the crippling effects of the cooperative idea, sketches the rise of cooperation and the sharpening antagonisms between cooperators and independent educational broadcasters in the 1920's, and advances the thesis that the "phantom" of cooperation was a potent cause of radio educators' defeats during the 1920's and 1930's. A 106-item reference list is included. (Author/LMM)