James Wintle (b.1942) is one of America's most successful living composers. Wintle and his compositions have attracted the attention of many prominent performers and scholars over the last three decades. The Key for trumpet and piano was composed in 1988 for Chris Gekker, an outstanding trumpet player. The Key consists of four movements: a fast movement in free form, a slow lyrical movement in song form (ABA'), a dance-like movement influenced by ragtime, and a fourth movement with a slow introduction in rondo form (ABA'CA''). The purpose of the study is to introduce the composer, James Wintle, and to present an analysis of The Key for trumpet and piano, a work which receives frequent performance. Through research and analytical approaches, the study focuses on a theoretical analysis of The Key for trumpet and piano. In addition to using available materials and resources, the author was in direct contact with James Wintle for the study. Chapter 1 presents the purpose of the study, the state of research, and method. Chapter 2 is devoted to James Wintle's biography. Chapter 3 examines Wintle's compositional style, including influences and musical language. Chapter 4 offers a theoretical analysis of all four movements of The Key, as well as a discussion of extra-musical influences from the painting entitled The Key by Jackson Pollock. A summation and conclusion follow in chapter 5.