In 1934, Harris joined the faculty of the Westminster Choir School (now College), having been recommended to the School's founder and president, John Finley Williamson, by Carl Engel, Chief of the Music Division of the Library of Congress, whom the composer had met during his research there (Engel was later to join the firm of G. Schirmer and seems to have been responsible for securing with that firm Harris's first longterm publisher's contract). Johana joined him the following year, the two remaining at Westminster until 1938, teaching the regular sessions there, summers at Juilliard. Harris also taught one summer (1938) at Princeton University.
The importance of his work during the previous decade with Farwell and his sojourn abroad with Boulanger notwithstanding, Harris's accomplishments during the 1930s marked these years off as comprising the crucial period in his career, the one in which he achieved his initial, and possibly greatest, success as a creative figure of national importance, the premiere by Koussevitzky and the Boston Symphony Orchestra in 1939 of the Symphony No. 3 serving as a capstone for the decade. This success was reinforced by the appearances of the first recordings of his music, the Symphony 1933 and the Concerto for Piano, Clarinet, and String Quartet bringing their composer the dual distinctions of being the first symphony and major chamber work by an American to be recorded commercially. In addition, his works first saw print during the 1930s, with issues by the Cos Cob Press (the Sonata for Piano and Concerto for Piano, Clarinet, et at) and Henry Cowell's New Music Quarterly (the Trio) and a series of publications of both original compositions and transcriptions and editions of the works of other composers emanating from G. Schirmer. The decade also marked a deepening of his acquaintance with the literature of Anglo-Celtic and Black folk music through another period of Library of Congress research, undertaken this time in the institution's extensive folk music holdings as part of the preparation for an extensive choral anthology he collaborated on with Jacob Evanson (eventually issued as Singing Through the Ages). Finally, of course, there was his marriage to Johana, which provided him with the artistic companionship of a mate of comparable genius, a spur to his creative work, and a measure of domestic stability.
