A student of Paul Hindemith, Etler is noted for his highly rhythmic, harmonically and texturally complex compositional style, taking inspiration from the works of Bartók and Copland as well as the dissonant and accented styles of jazz.
Though he played with the Indianapolis Symphony in 1938, he abandoned his orchestral life shortly thereafter to focus on his increasingly successful compositional career (which earned him two Guggenheim Fellowships during this period). In 1942 he joined the faculty at Yale University as conductor of the university band and instructor of wind instruments, where he began his studies with Hindemith. He also taught at Cornell University and University of Illinois before accepting a position at Smith College, which he held until his death.
Notable works include his two woodwind quintets (from 1955 and 1957), a bassoon sonata, the 1963 "Quintet for Brass Instruments", and "Fragments" for woodwind quartet.
Etler is also the author of Making Music: An Introduction to Theory, an introductory-level theory text published posthumously in 1974.
Etler received several important commissions from major orchestras and a number of these works were premiered by prominent conductors including Fritz Reiner, who conducted the premiere of the Symphonietta in 1941, his Passacaglia and Fugue in 1947 with the Pittsburgh Symphony Orchestra, and George Szell, who commissioned the Concerto in One Movement for the Cleveland Orchestra in 1957. His Concerto for Wind Quintet and Orchestra was premiered by the Japan Philharmonic in 1960 and was subsequently performed in 1962 by both the New York Philharmonic, under the baton of Leonard Bernstein, and the Boston Symphony Orchestra, under the direction of Erich Leinsdorf.
His Concerto for Brass Quintet, String Orchestra and Percussion and his Sonic Sequence for Brass (both composed in 1967), were recorded by the National Orchestra Association under conductor John Barnett for Composers Recordings, Inc.
His large scale works include:
Music for Chamber Orchestra (1938)
Passacaglia and Fugue (1947)
Concerto for String Quartet and Orchestra (1948)
Dramatic Overture for Orchestra (1956)
Concerto for Wind Quintet and Orchestra (1960)
Concerto for Brass Quintet, String Orchestra and Percussion (1967)
Concerto for Cello and Chamber Orchestra (1970)
Other notable chamber and solo works include his two woodwind quintets (from 1955 and 1957), a bassoon sonata, the 1963 "Quintet for Brass Instruments," and "Fragments" for woodwind quartet.