The objective of this paper is to show how Olivier Messiaen's Mode de valeurs et d'intensites influenced the development of postwar serialism. Written at Darmstadt in 1949, Mode de valeurs is considered the first European work to organize systematically all the major musical parameters: pitch, duration, dynamics, articulation, and register. This work was a natural step in Messiaen's growth toward complete or nearly complete systemization of musical parameters, which he had begun working towards in earlier works such as Vingt regards sur 1'Enfant-Jesus (1944), Turangalila-symphonie (1946-8), and Cantyodjaya (1949), and which he continued to experiment with in later works such as Ile de Feu II (1951) and Livre d'orgue (1951). The degree of systematic control that Messiaen successfully applied to each of the musical parameters influenced two of the most prominent post-war serial composers, Pierre Boulez and Karlheinz Stockhausen, to further develop systematic procedures in their own works. This paper demonstrates the degree to which both Boulez' Structures Ia (1951) and Stockhausen's Kreuzspiel (1951) used Mode de valeurs as a model for the systematic organization of musical parameters.