Chapin began publishing poems in the late 1920s, in the popular press and in literary journals including Poetry.

[13][a] Chapin later attended Columbia University for "postgraduate work",[9][b] where she studied under Franz Boas, Max Eastman, and Kurt Schindler.

[21][22] Allen Tate, who would name her one of the inaugural Fellows in American Letters of the Library of Congress[23][24] was a friend of Chapin's, as was Alexis Léger, a poet who wrote as Saint-John Perse.

[19] Katherine remained in Washington for just under 40 years after her move in 1934, presumably with a short interlude in the mid-1930s during Biddle's term as a circuit judge; the family kept a house in Philadelphia as late as 1938.

[36][38] The New York Times, in a notice for And They Lynched Him on a Tree, called Lament "a dirge for the mother of a child who has been stolen and killed".

[40] Chapin wrote And They Lynched Him on a Tree (1940) while a federal anti-lynching bill sponsored by Representative Joseph A. Gavagan was being debated in the United States Congress;[41][42] scholar Catherine Reef argues that Chapin wrote And They Lynched Him "to persuade Congress to pass" the legislation.

Chapin's aunt Charlotte Osgood Mason, a white patron of artists of the Harlem Renaissance,[45] conceived the work in collaboration with Alain Locke, likely in spring 1939.

… [And They Lynched Him on a Tree] is more powerful than the Lament for the Stolen, but has the same skill at transforming a melodramatic situation into one of tragic depth and beauty.

[49]Still wrote to Chapin just over a week later, on August 18, 1939, to express his enthusiasm for the project: "I've long wished to add my voice to the general feeling against lynching, and have been waiting for the proper vehicle to present itself".

A notice by Still's wife Verna Arvey in the New York Times in advance of the premiere wrote:… Miss Chapin's poem is the voicing of her deep conviction that lynching is a serious flaw in the fabric of our American democracy, and her belief that this conviction is held by the majority of Americans in the South and the North.

In an article on Plain-Chant, Arvey quotes Chapin on the genesis of the work:An American poem had been germinating in my mind for a long time, but the final circumstance that thrust it into being was the fact that I had spent a few days in the company of some persons who were sympathetic with the Fascists, whose talk showed me vividly the gap between totalitarianism and the American democracy in which I believed.

The emotion of the poem began there; it found completion when we stood behind President Roosevelt in the sunshine at Key West … while he made a fine radio broadcast opening the San Francisco Fair.

Harriet Monroe, reviewing Chapin's collection Outside of the World in Poetry in 1932, noted "the quietly meditative tone of the poems, the poet's sensitiveness to the beauty of common experiences, and her compact and imaginative expression of them".

Katharine Chapin has an ideology … but lacks a sufficient volume of texture in her technique to give her work the dualism of images and logical substance which makes for major poetry.

[64]A review in Poetry of Chapin's last collection The Other Journey (1959), advanced a similarly lukewarm assessment: Seriousness and technical competence, even together, do not necessarily sustain one's interest in a group of poems.

… The whole book is curiously lacking in personal impact …[65]Robert Hillyer, however, reviewing The Other Journey in The New York Times, said it showed an "easy lyric grace" and "unobstructed communication".

[67] The nomination was endorsed by several senators and Nelson Rockefeller, the Vice President of the United States,[68] but she was ultimately not selected for the honor.

Chapin's play Sojourner Truth, about the early years of the historical figure of the same name, was produced by the American Negro Theater in 1948.