jats:pNew light is shed on the song culture of Sankt Gallen almost a century before its earliest notated sources through consideration of the poetic section of a manuscript copied at the Abbey shortly after the year 800, i.e. the second part of Leiden, Universiteitsbibliotheek Vossianus Lat. Q. 69. The predominantly Merovingian accentual Latin verse (jats:italicrhythmi</jats:italic>) and metrical verse by the late-antique poet Prudentius (his jats:italicLiber Cathemerinon</jats:italic> and jats:italicLiber Peristephanon</jats:italic>) were written out in song forms. It is newly proposed that Prudentius’ verse from the jats:italicLiber Peristephanon</jats:italic> was arranged into a liturgical cycle. The poetic section of the Leiden manuscript is accordingly understood as a collection of songs, which prompts reflection on the way in which earlier sung jats:italicversus</jats:italic> at Sankt Gallen may have provided models for the later jats:italicLiber ymnorum</jats:italic>. Witnesses to the song culture of Sankt Gallen in the first half of the ninth century are re-examined and a leading role during this period for the nearby Abbey of Reichenau is proposed. Finally, it is suggested that Iso’s advice to Notker that jats:italicsingulae motus cantilenae singulas syllabas debent habere</jats:italic> was at least partly informed by the existing tradition of sung jats:italicversus</jats:italic> at both abbeys.</jats:p>