First Published in 1987. This study presents the background for the sacred musical patronage at the court, with specific reference to the polyphonic settings of the Mass Ordinary - during the reign of Holy Roman Emperor Rudolf II (1576-1612). One function of the present work is to collect the various relevant data concerning the chapel and the Mass, and to demonstrate basic relationships at the court. This study approaches the chapel of Rudolf II through archival research, musical sources, and comparing the compositional process of its composers. The goal is a better understanding of the sacred musical practice at the chapel.