Wolfgang Amadeus Mozart's Maurerische Trauermusik, K. 477, is often placed between his Mass in C Minor and his Requiem. The reason being that the three works share similar motivic content. The Maurerische Trauermusik is perceived as a stepping-stone between the two more famous works and is often overlooked. The genesis of the Maurerische Trauermusik is the issue. Mozart recorded in his thematic catalogue that the piece was composed in July of 1785 for the funeral of two lodge brothers; however, the two lodge brothers did not die until November of the same year. The reason Mozart composed the Maurerische Trauermusik was because it was used as music for a Masonic ritual ceremony to ascend to the degree of Master Mason. Noted Mozart scholars Philippe Autexier and Heinz Schuler attempt to decipher the origins of this piece; however, both of their arguments are based on historical context. Historical context alone is not sufficient enough to provide an accurate understanding of the genesis of the Maurerische Trauermusik. An analysis of the musical elements that relate to Freemasonry are essential to understanding the piece. The goal of this thesis is to explain how the Maurerische Trauermusik was originally used as a piece of ritual music. Mozart left clues in the music itself to show the enlightened its true meaning. Using Mozart's history with the Brotherhood, an analysis of the musical symbols that relate to Freemasonry, and referencing other Masonic works by Mozart, one will see that the Maurerische Trauermusik was used as program music in the ritual to ascend to the degree of Master Mason.