Trained as an engineer, Iannis Xenakis is known for having used mathematical models in his compositions and for developing a formalization of music. This book presents Xenakis’s main theories from an analytical perspective without calling for special knowledge of mathematics. It features numerous musical examples and relies on detailed analyses to explain Xenakis’s compositional procedures, yielding new insight into the relation between theory and practice in the composer’s music. As a comprehensive study, it also reveals for the first time the extent to which Xenakis borrowed from his earlier works.