Polyphonie X

Polyphonie X (1950–51) is a three-movement composition by Pierre Boulez for 18 instruments divided into seven groups, with a duration of roughly 15 minutes. Following the work's premiere, Boulez withdrew the score, stating that it suffered from "theoretical exaggeration". (In a 1974 interview, he referred to it as a "document" rather than a "work".)

Despite Boulez's dissatisfaction with the piece, it played a key role in his development: one writer called it "the linchpin connecting Boulez's early mastery of gesture and contour... with his later interest in large ensembles and grand forms", his "brave 'first attempt' to produce a work that exhausted a particular musical technique with large orchestral forces by developing an expansive, additive structure at the earliest stages of composition", and "one of the purest representations of Boulez's first turn toward integral serialism".