He conceived of the symphony as a composition, primarily orchestral in medium, expressing a broad range of emotions and entailing considerable complexity in the working-out of its materials. Possibly his most significant contribution to the genre is his exploration of the single-movement design: four of the symphonies employ this format, most of these featuring one or more melodic ideas that function thematically by recurring at strategic points, thereby providing an element of long-range unification. In his multi-movement symphonies, the characters and tempos of the individual movements often correspond with those of the Classic-period sonata-cycle; however, for the structural designs of these, and of the one-movement symphonies as well, Harris preferred an autogenetic process (described below).
Four symphonies feature a chorus (the Folksong Symphony, Symphony No. 10, the Bicentennial Symphony 1976, and Symphony for Voices-the last-named an a cappella work), and one, No. 12, contains an important part for solo voice/speaker; there is also a Symphony for Band. The composer excluded from his numbered canon this last work, as well as the Symphony for Voices and the early orchestral Symphony-American Portrait 1929.
Symphony No. 3, often regarded as the finest of his works in the genre, is his most widely-performed and best-known large work. But Nos. 5, 6, 7, 8, and the Folksong Symphony are no less successful achievements, revealing a wide variety of characters and an often high level of technical accomplishment.
Harris's chamber compositions, though similar to the symphonies in the nature and treatment of their materials, tend to be more intensively polyphonic, a feature that results in a greater characterization of the individual lines. Most employ strings, from which the composer sometimes demands a nearorchestral sonority. Among his best works in the genre are the Concerto for Piano, Clarinet, and String Quartet; the Quintet for Piano and Strings; Three Variations on a Theme (Quartet No. 2) and Quartet No. 3; the Sonata for Violin and Piano; and Soliloquy and Dance for viola and piano. The Quintet, whose three interconnected movements are based on a single theme (like the Three Variations), is noted for its breadth of architecture and intensity of expression, while Quartet No. 3 summarizes Harris's approach to modality and his early treatment of counterpoint.
