The early masses, from printed collections of 1542 and 1557, reveal Ruffo's command of contrapuntal techniques and traditions; two of these works are based on motets by Richafort and Jacquet of Mantua. The four later masses, written in the 1560s and 1570s, were composed under the direct influence of the Counter Reformation and exhibit drastic changes in procedure aimed at achieving an "intelligible" style.