Rossini's Petite Messe is a departure from the more traditional masses of Mozart and Schubert, featuring only piano, choir, and harmonium (a cousin of the reed organ that sounds similar to an accordion.) Some movements employ the entirety of the instrumentalists and vocalists, such as the opening Kyrie, while others only use one or two elements, such as the tenor dominated Domine Deus and the the Preludio Religioso (movement 12), which features only piano.