This study explores Kondakarnoie Pienie, a musical phenomenon that flourished in Kievan Rus' from the 11th-13th centuries and is preserved in only five manuscripts. Stimulated by the global digitization initiatives undertaken by the major holdings East and West, previously inaccessible primary source material has come available. As a result the current investigation is a reassessment of earlier work accomplished. It addresses aspects of musical palaeography, liturgical context and function, and performance practice. The music examined is the chant cycles for the Forefeast, Christmas and Epiphany celebrations, a substantial body of comparable musical material that furnishes explicit evidence of the appropriation of Byzantine cathedral chanting practices by the medieval Slavs.