For over forty years Iannis Xenakis has been one of the major figures in contemporary music. In all that time, there has not been a study of his music published in English. This volume leads the reader along the trajectory of Xenakis's compositional development, presenting the works together with the technical and conceptual innovations he has introduced along the way. Particular works are examined in greater detail as signposts marking new stages in the composer's creative journey, from the early, unpublished works to the breakthrough pieces Metastasis and Pithoprakta, through the oft-discussed decade of formalization to the evolving styles of the succeeding three decades. Harley approaches the music from the point of view of a musician; his thesis rests upon the conviction that Xenakis's theoretical formulations can be explained and understood without recourse to complicated mathematics. This "scientific" feature of the composer's own explications of his work has baffled and often alienated manywho have responded strongly to the music. The book also includes an up-to-date bibliography, discography, and a list of works.