Instrumental in forging a distinctly American style of composition, in his later years he was often referred to as "the Dean of American Composers" and is best known to the public for the works he wrote in the 1930s and 1940s in a deliberately accessible style often referred to as Populist and which the composer labeled his "vernacular" style. Works in this vein include the ballets Appalachian Spring, Billy the Kid and Rodeo, his Fanfare for the Common Man and Third Symphony. The open, slowly changing harmonies of many of his works are archetypical of what many people consider to be the sound of American music, evoking the vast American landscape and pioneer spirit. In addition to his ballets and orchestral works, he produced music in many other genres including chamber music, vocal works, opera and film scores.
After some initial studies with composer Rubin Goldmark, Copland traveled to Paris, where he studied at first with Isidor Philipp and Paul Vidal, then with noted pedagogue Nadia Boulanger. He studied three years with Boulanger, whose eclectic approach to music inspired his own broad taste in that area. Determined upon his return to the US to make his way as a full-time composer, Copland gave lecture-recitals, wrote works on commission and did some teaching and writing. He found composing orchestral music in the "modernist" style he had adapted abroad a financially contradictory approach, particularly in light of the Great Depression. He shifted in the mid-1930s to a more accessible musical style which mirrored the German idea of Gebrauchsmusik , music that could serve utilitarian and artistic purposes. During the Depression years, he traveled extensively to Europe, Africa, and Mexico, formed an important friendship with Mexican composer Carlos Chávez and began composing his signature works.
During the late 1940s Copland felt a need to compose works of greater emotional substance than his utilitarian scores of the late 1930s and early 1940s. He was aware that Stravinsky, as well as many fellow composers, had begun to study Arnold Schoenberg's use of twelve-tone techniques. In his personal style, Copland began to make use of tone-rows in several compositions. He incorporated serial techniques in some of his later works. Among them, his "Piano Quartet", "Piano Fantasy", "Inscape" for orchestra and "Connotations ." From the 1960s onward, Copland's activities turned more from composing to conducting. He became a frequent guest conductor of orchestras in the US and the UK and made a series of recordings of his music, primarily for Columbia Records.