While there he studied with Nikolai Lopatnikoff and Frederick Dorian and wrote music criticism for the Pittsburgh Post-Gazette.
During this time he also spent summers at the Berkshire Music Center at Tanglewood where he studied with Darius Milhaud and Aaron Copland.
Trimble was also the music critic for The Nation (1957–62), the Washington Evening Star (1963–8) and Stereo Review (1968–74).
[1] In 1971 he joined the faculty of the Juilliard School and in 1973 he became the first composer-in-residence at Wolf Trap Farm Park.
His music is published by ACA, Belwin-Mills, Duchess, Leeds, C. F. Peters, and Presser.