Chiefly prose and verse manuscripts, together with correspondence, advertisements, biographical material, contracts, drawings. newspaper clippings, notes, photographs, press releases, research material, royalty statements, and other papers. Includes holograph and typescript drafts, galley and page proofs, and printed versions of aphorisms, articles, book reviews, books, columns, essays, etymological dictionaries, plays, poems, poetry reviews, radio and television scripts, and speeches and lectures.

The collection primarily focuses on Ciardi's career as poetry editor and writer of the column, "Manner of Speaking," for the Saturday Review and also as director of the Bread Loaf Writers' Conference of Middlebury College, as a member of the faculty at Harvard University, Rutgers University, and University of Missouri at Kansas City, as editor of poetry and science fiction at Twayne Publishers, and as host of the CBS television series, "Accent" and the National Public Radio series, "A Word in Your Ear."

Ciardi's English translation of Dante Aligheri's Divine Comedy, a twenty-year project, is also documented as is the publication of twenty-four of his books and the works of his associates, Stephen Vincent Benét, Richard Eberhart, John Haynes Holmes, Archibald MacLeish, Fletcher Pratt, Shloime ("Selwyn") Schwartz, Studs Terkel, and Peter Robert Edwin Viereck. Other projects noted include his poetry for children, anthologies of essays and poetry, limericks, and writings for textbooks, recordings of his poetry readings, his appearances at the Library of Congress, and other speaking engagements.

Other aspects of the collection include Ciardi's student days at Bates College and Tufts University, his support of Henry Agard Wallace and the Progressive Party, the trial regarding William S. Burroughs's book, "Naked Lunch," Ciardi's refusal to attend a racially segregated meeting of the Alabama Education Association, his role as an advisor for student publications at Tufts University, his involvement with campus unrest in the 1960s, his fellowship at the American Academy in Rome, and his association with the American Academy and Institute of Arts and Letters, College English Association, and Garden State Choral Society. Also includes material on art exhibitions, censorship, English language instruction, modern art, and plagiarism.

Correspondents include George Abbe, Léonie Adams, Roy Prentice Basler, Norman Cousins, J. Frank Dobie, Richard Eberhart, Dudley Fitts, Robert Frost, John Haynes Holmes, Dan Jaffe, X. J. Kennedy, Alfred Kreymborg, Archibald MacLeish, John Frederick Nims, Robert Pack, Theodore Roethke, Muriel Rukeyser, Winfield Townley Scott, William Sloane, May Swenson, Henry F. Thoma, and Richard Wilbur.