James Weldon Johnson"s major contribution to the Harlem Renaissance explosion of black American writing was his book of poems, God’s Trombones: Seven Negro Sermons in Verse, published in 1927. For almost ten years Johnson worked on these folk sermons in verse whenever the demands of NAACP work relented enough to make writing possible. "The Creation" was published in 1918, and two others were published in magazines during the mid-1920s. In this work he followed the principles he had developed in writing the long preface to The Book of American Negro Poetry:

What the colored poet in the United States needs to do is something like what Synge did for the Irish; he needs to find a form that will express the racial spirit by symbols from within rather than symbols from without, such as the mere mutilation of English spelling and pronunciation. . . . He needs a form that is freer and larger than dialect . . . a form expressing the imagery, the idioms, the peculiar terms of thought and distinctive humor and pathos, too, of the Negro. (Quoted in Johnson’s introduction to God’s Trombones)

The completed book presents seven sermons—"The Creation," "The Prodigal Son," "Go Down Death--A Funeral Sermon," "Noah Built the Ark," "The Crucifixion," "Let My People Go," and "The Judgment Day"--preceded by an opening poem, "Listen, Lord--A Prayer." While the book as a whole does not have a narrative structure, as the sermons stand independent of one another, the sermons as poems bring together the narrative element of the stories from the Bible on which they are each based, the narrative/dramatic moment of the sermon, and the lyric quality of the folk preachers language.

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While remaining connected to the late Romantic dramatic monologue form that Paul Laurence Dunbar and other black American poets had long favored, Johnson here admits the free verse tradition of Walt Whitman to mingle with the rhetorical imagery and verbal excitement of the folk preacher. Not forced to represent speech rhythms with mechanical metrics or distracting rhymes, Johnson is able to focus attention on the metaphoric and ironic creativity of the African American oral tradition. His preacher connects a world of Bible-based ideas to the congregation/reader's mundane reality.

Johnson is remarkably successful in creating a poetic equivalent of the language of what he calls in the introduction "the old time Negro preacher." In "The Creation," the first and most famous of these poems, he creates that old-time preacher’s voice as a mixture of vibrant folk idiom, King James version grandeur, and apt metaphor. Thus God makes man of the clay from the riverbed while kneeling "like a mammy bending over her baby." The rather abstract and distant creator of the Bible text is humanized by the preacher’s narrative details and poetic touches.

The imagery and rhetoric of the poems draw upon the traditions of sacred song as well as sermons. In "Let My People Go" Johnson echoes his favorite spiritual, while at the same time addressing both black readers and white.

Commonly accepted as James Weldon Johnson's highest achievement in poetry, God's Trombones demonstrated in art the dignity and power of African American folk culture. With its illustrations by Aaron Douglas, the collection has enjoyed continuous popularity among scholars and general readers alike.