Milton Babbitt is accepted as one of the earliest adopters of integral serialism, a label that has been applied to a number of European composers including Pierre Boulez, Karlheinz Stockhausen, Luige Nono, and Jean Barraqué. What sets Babbitt apart from this group encompasses both his compositional techniques and his roots as an American musician. Through extensions of twelve-tone techniques pioneered by Arnold Schoenberg and Anton Webern, Babbitt explored the possibilities of this new approach to pitch structure not so much to recapture historical modes of music making but to build a way of making music derived from a set of first principles emerging from using relationships amongst aggregates of the twelve pitch-classes. He also developed ways of thinking about temporal relationships that adapted his insights into pitch relationships in order to create a compositional world in which to be creative. The chapter traces this development over the span of his career.