Government investigations into the motion picture industry are well-documented, as is the widespread blacklisting that was concurrent. Not nearly so well documented are the many investigations of musicians and musical organizations which occurred during this same period. The degree to which various musicians and musical organizations were investigated varied considerably. Some warranted only passing mention, while others were rigorously questioned in formal Congressional hearings. Hanns Eisler was deported as a result of the House Committee on Un-American Activities' (HUAC) investigation into his background and activities in the United States. Leonard Bernstein, Marc Blitzstein, and Aaron Copland are but a few of the prominent composers investigated by the government for their involvement in leftist organizations. The Symphony of the Air was denied visas for a Near East tour after several orchestra members were implicated as Communists. Members of musicians' unions in New York and Los Angeles were called before HUAC hearings because of alleged infiltration by Communists into their ranks. The Metropolitan Music School of New York, led by its president-emeritus, the composer Wallingford Riegger, was the subject of a two day congressional hearing in New York City. There is no way to measure either quantitatively or qualitatively the effect of the period on the music but only the extent to which the activities affected the musicians themselves. The extraordinary paucity of published information about the treatment of the musicians during this period is put into even greater relief when compared to the thorough manner in which the other arts, notably literature and film, have been examined. This work attempts to fill this gap and shed light on a particularly dark chapter in the history of contemporary music.