After returning from the war, Hindemith again took to the concert stage, having switched to viola in 1919. In 1923 he was invited to join the administrative committee of the Donaueschingen Festival, a group over which he exerted an ever increasing amount of control; programming works of such composers as Schoenberg and Webern. The next year he married Gertrud Rottenberg, the daughter of the conductor of the Frankfurt Opera Orchestra, an ensemble in which Hindemith had been playing. In 1927 he received an appointment as professor of composition at the Hochschule für Musik in Berlin. In addition to maintaining an active performing career, Hindemith soon developed a strong interest in teaching, and even took on an evening class at the Volksmusikschule NeuKolln.
Early in 1934, the Nazi party began a campaign to discredit Hindemith, which culminated in a boycott of the composer's works announced by the Kulturgemeinde in November of that year. In January 1935, Hindemith was given a six-month leave from the Hochschule. However, as the boycott of his music was not endorsed by the music division of the Nazi party until 1937, Hindemith was allowed not only to return to teaching, but also to undertake a series of concert tours abroad, to have his music published, and to enter into an agreement with the government of Turkey to build an organized musical life in that country. However, in 1937, Hindemith left Germany for Switzerland, and in 1940 came to the U.S.
After a series of lecture and teaching engagements which had been arranged by friends, Hindemith took a position at Yale, teaching composition and, from 1945 to 1953, conducting the Collegium Musicum. In 1946, Hindemith became an American citizen. In 1951 he accepted a position at the University of Zurich and, after retiring from Yale in 1953, took up permanent residence in Switzerland. After retiring from his post in Zurich, in 1955, he became more active as a conductor. In November 1963, he was taken ill and transferred to a hospital in Frankfurt, where he died of acute pancreatitis.