He has been described as a modernist,[1][2][3][4] a neoromantic,[5] a neoclassicist,[6] and a composer of "an Olympian blend of humanity and detachment"[7] whose "expressive voice was always carefully muted" until his late opera Lord Byron which, in contrast to all his previous work, exhibited an emotional content that rises to "moments of real passion".

While studying in Paris he was influenced by several French composers who were members of "Les Six" including: Darius Milhaud, Francis Poulenc, Arthur Honegger, Georges Auric, and Germaine Tailleferre.

Later he and Grosser lived at the Hotel Chelsea, where he presided over a largely gay salon that attracted many of the leading figures in music and art and theater, including Leonard Bernstein, Tennessee Williams, and many others.

He also encouraged many younger composers and literary figures such as Theodor Adorno, Ned Rorem, Lou Harrison, John Cage, Frank O'Hara, and Paul Bowles.

[13] Thomson incorporated musical elements from Baptist hymns, Gregorian chants and popular songs into both scores while demonstrating a restrained use of dissonance.

Thomson incorporated folk melodies and religious musical themes into the film score and subsequently composed an orchestral suite of the same name which was recorded by Leopold Stokowski and the Hollywood Bowl Symphony Orchestra in 1946 for RCA Victor (# 11-9522,11-9523).

[14][15] In 1938 he also formed a collaboration with Lorentz and the operatic singer Thomas Hardie Chalmers on the documentary film The River for the United States government's Farm Security Administration.

[18] Subsequently, in 1948 he collaborated with the director Robert J. Flaherty on the docufiction film Louisiana Story, for which he received the Pulitzer Prize for Music in 1949.

[29][30] Thomson became a sort of mentor and father figure to a new generation of American tonal composers such as Ned Rorem, Paul Bowles and Leonard Bernstein, a circle united as much by their shared homosexuality as by their similar compositional sensibilities.

[31] Women composers were not part of that circle, and one writer has suggested that, as a critic, he selectively omitted mention of their works, or adopted a more passive tone when praising them.