International festival of contemporary music which has been taking place in Warsaw since 1956. The only such festival available for the Soviet composers in that time. This forum became their opportunity to get performed as well as get acquainted with their Western counterparts. The Warsaw Autumn introduced Soviet composers to the music of Pierre Boulez, Luigi Nono, John Cage, Karlheinz Stockhausen, and Krzysztof Penderecki, among others.