Mass is a musical theatre work composed by Leonard Bernstein with text by Bernstein and additional text and lyrics by Stephen Schwartz. Commissioned by Jacqueline Kennedy, it premiered on September 8, 1971, conducted by Maurice Peress and choreographed by Alvin Ailey. The production used costume designs by Frank Thompson. The performance was part of the opening of the John F. Kennedy Center for the Performing Arts in Washington, D.C. Mass premiered in Europe in 1973, with John Mauceri conducting the Yale Symphony Orchestra in Vienna.

Kristjan Järvi is an Estonian American conductor, composer and producer. Born in Tallinn, Estonia, he is the younger son of the conductor Neeme Järvi and brother of conductor Paavo Järvi and flutist Maarika Järvi.