Private study piano with, David Saperton with, Clarence Adler, 1934-1937; private study conducting with, Fritz Reiner faculty, Sarah Lawrence College, 1939-1941; faculty, Curtis Institute Music, 1937-1941; Doctor of Music (honorary), Cincinnati College Music, 1954; Doctor of Humane Letters (honorary), Edinboro University of Pennsylvania, 1990.
From 1939 to 1941 he taught at Sarah Lawrence College in New York City. In 1941 and 1942, he was a pianist and conductor at the Berkshire Music Center under Serge Koussevitzky. In 1949, he was appointed music director of the Dallas Symphony Orchestra, and he held this position until 1958.
In 1953, Hendl became the music director of the Chautauqua Symphony Orchestra.
He remained with Chautauqua until temporary ill health necessitated his resignation in 1972. He was also active in the Symphony of the Air and conducted its 1955 tour of east Asia.
At the same time, he was the first artistic director of the Ravinia Festival and served there from 1959 to 1963. He left the Chicago Symphony Orchestra in 1964.
From 1964 to 1972, Hendl served as director of the Eastman School of Music at Rochester, New York, and was also musical adviser to the Rochester Philharmonic Orchestra and its part-time conductor.
In 1976 Hendl was appointed music director of the Erie Philharmonic in Erie, Pennsylvania. In 1990, he became professor of conducting at Mercyhurst College in Erie. An advocate of contemporary music, he conducted the premieres of Peter Mennin"s Symphony Number.
3 with the New York Philharmonic Orchestra in 1947, Bohuslav Martinů"s Piano Concerto Number.
3 with Rudolf Firkušný and the Dallas Symphony in 1949, Villa-Lobos"s Cello Concerto Number. 2 with Aldo Parisot and the New York Philharmonic Orchestra in 1954, and the American premiere of Kabalevsky"s Requiem with students of the Eastman School in 1965.
He composed incidental music for various stage productions and made several orchestral transcriptions. He was inducted as a National Patron of Delta Omicron, an international professional music fraternity on December 1, 1960.
His best-selling recordings include violin concerti featuring Jascha Heifetz, Henryk Szeryng, and Erick Friedman and piano concerti featuring Van Cliburn and Gary Graffman.
Hendl died in Harborcreek Township, Pennsylvania, after suffering from heart and lung disease.
Married Barbara Heisley. 1 dau by previous marriage, Susan.