Our prayers and prayerbooks for the High Holidays have evolved through time and space. Through examining treasures of the Klau Library, we will explore some of the earliest manuscript prayerbooks of the rites from Babylonia and the Land of Israel (preserved in the Cairo Genizah), as well as prayerbook manuscripts from different Jewish communities around the world (including Kaifeng, China), the first printed prayer book (from Italy in the fifteenth century), and the earliest notated high holiday music of the Spanish-Portuguese rite (1823, from the Reform Hamburg Temple!).