The electroacoustic works of the Greek-French composer Iannis Xenakis (1922-2001) captivate with their radical ideas, sounds and compositional models. They were often conceived as multimedia works for specific locations and architectures. The richness of the approaches and processes gave rise to an extensive body of sources. Therefore, this volume is particularly dedicated to a philological approach, combining contributions by companions of Xenakis and renowned experts in Xenakis research with studies in philology of electroacoustic music. It concludes with a roundtable discussion of the performance of these electroacoustic works, thus linking the philological questions back to musical practice.