This book presents the most recent findings of twenty of the foremost European and North American researchers into the music of the Middle Ages. The chronological scope of their topics is wide, from the ninth to the fifteenth century. Wide too is the range of the subject matter: included are essays on ecclesiastical chant, early and late (and on the earliest and latest of its supernumerary tropes, monophonic and polyphonic); on the innovative and seminal polyphony of Notre-Dame de Paris, and the Latin poetry associated with the great cathedral; on the liturgy of Paris, Rome and Milan; on musical theory; on the emotional reception of music near the end of the medieval period and the emergence of modern sensibilities; even on methods of encoding the melodies that survive from the Middle Ages, encoding that makes it practical to apply computer-assisted analysis to their vast number. The findings presented in this book will be of interest to those engaged by music and the liturgy, active researchers and students. All the papers are carefully and extensively documented by references to medieval sources.