Olivier Messiaen (1908-1992) is known for his unique composition style. Incorporating complex rhythms, harmony and melodies, Mass of Pentecost is no exception to the composer's popular, distinctive style. Composed in 1949-1950, the Organ Mass is thought to be based on twenty years of improvising at Saint Trinity Church in Paris where Messiaen was organist. Mass of Pentecost is in five movements; 1) Entrance 2) Offertory 3) Consecration 4) Communion 5) Recessional Influences of birdsong are depicted within the piece, reflecting the composer's interest in ornithology. The first movement also contains the use of Greek rhythms. Mass of Pentecost is essential to all advanced organists seeking to expand and vary their repertoire.