Egon Wellesz presents here an in-depth survey of Christian music in the Byzantine tradition. Originally published as two separate articles, Wellesz’s full study is published here as one text. In the first part of the article, Wellesz describes the present state of research and the problems inherent in such a survey. After surveying and assessing previous research, Wellesz proceeds with an analysis of several pieces of music from the Eastern Christian tradition. In the second part of the study, Wellesz focuses on the notation and symbols used in the manuscript tradition. This survey provides a concise but thorough overview of the study of Byzantine music that would be helpful for novices and specialists interested in historical studies of music.