Research in the 20th and 21st centuries into historical performance practice has changed not just the way performers approach music of the 17th and 18th centuries but, eventually, the way audiences listen to it. This volume, beginning with a 1915 Saint-Saens lecture on the performance of old music, sets out to capture musicological discussion that has actually changed the way Baroque music can sound. The articles deal with historical instruments, pitch, tuning, temperament, the nexus between technique and style, vibrato, the performance implications of musical scores, and some of the vexed questions relating to rhythmic alteration. It closes with a section on the musicological challenges to the ideology of the early music movement mounted (principally) in the 1990s. Leading writers on historical performance practice are represented. Recognizing that significant developments in historically-inspired performance have been led by instrument makers and performers, the volume also contains representative essays by key practitioners.