Libby Larsen (b. 1950), one of America’s leading composers, has written in nearly every genre of classical music. Among her catalogue of vocal music are choral works, operas, art song, and song cycles. Larsen’s song cycles are known for their texts that portray strong women and are written by female writers. Larsen’s declamatory text settings, which are influence by her training in Gregorian chant, capture the struggles and triumphs of these strong female figures. Her recitative-like melodies bring to life these women such as the artist Mary Cassatt (1844-1926) in Larsen’s song cycle Mary Cassatt (1844-1926): Seven songs for mezzo-soprano, solo trombone, and orchestra (with 15 projections of Cassatt’s paintings) (1994). In addition to her plainchant-influenced vocal melodies, Larsen utilizes the solo trombone to communicate Cassatt’s inner voice and projections of Cassatt’s paintings to demonstrate the artist’s evolution. The use of the trombone in this song cycle arose from the terms of the commission. The Grand Rapids Symphony Orchestra and The Keller Foundation commissioned Mary Cassatt to be premiered by Fred P. Keller’s (b. 1944) wife, Linn Maxwell Keller (1943-2016). Fred Keller chose the trombone as the solo instrument because he thought it would be an interesting combination with mezzo-soprano and orchestra. Transcribed interviews published in journals, newspapers, and dissertations, my personal interview with Larsen, a review of biographical information about the composer, and my own analysis of the score will provide a thorough background of Larsen’s use of this ensemble in this song cycle. Few song cycles in modern repertoire are accompanied by a full orchestra and utilize a solo instrument as an equal partner to the voice. This dissertation will bring to the forefront an awareness of Mary Cassatt and will provide thorough background information about the composer and the artist and an analysis of the score to support performances of this song cycle.