This article traces the processes of style-forming tendencies formation of liturgical singing at the Russian Orthodox Church, in 15th – 17th c. Two musical phenomena were chosen for study: Znamenny chant and Demestvenny razpev. Both are associated with Russian Pre-Renaissance and Transition periods. There, ongoing transformation is obvious and significant, affecting all music components, like intonation, modes, composition, notation and orthography design, on all levels of hierarchy (popevka – chant – cycle of chants). Master singers strive to enhance singing’s intonation scope, synthesizing spiritual singing with folk singing; broaden modal and compositional thinking, and develop an emotionally solemn style. These factors match the main Middle Ages’ tendency of gradual expansion of “allowed freedom” in means of expression.