Correspondence including 219 volumes of letterpress books (1890-1920), speeches and addresses, presidential and judicial files, legal papers and notebooks, family papers and letters, business and estate papers, engagement calendars, guest lists, scrapbooks, clippings, printed matter, memorabilia, and photographs documenting Taft's career as U.S. solicitor general (1890-1892), U.S. circuit court judge (1892-1900), president of the U.S. Philippine Commission (1900-1901), governor of the Philippines (1901-1904), secretary of war in Theodore Roosevelt's cabinet (1904-1908), president of the United States (1909-1913), professor of constitutional law at Yale Law School (1913-1921), and chief justice of the U.S. Supreme Court. Also documents Taft's service as president of the American Bar Association (1913), president of the League to Enforce Peace (1915), and member and cochairman of the National War Labor Board (1918-1919).

Family members respresented include Taft's father, Alphonso Taft, U.S. secretary of war (1876), attorney general (1876-1877), and minister to Austria-Hungary (1882-1884) and to Russia (1884-1885); his mother, Louise Maria Torrey Taft, civic leader and advocate of the kindergarten movement; his wife, Helen Herron Taft; and his aunt, feminist Delia C. Torrey. Correspondence among these and other Taft family members reflects social and intellectual life in the United States during the late 19th and early 20th centuries. Also includes desk diaries and other papers of President Taft's private secretary, Fred W. Carpenter.

Correspondents include Nelson W. Aldrich, Chester Alan Arthur, Robert Bacon, Richard Achilles Ballinger, Albert Jeremiah Beveridge, Mabel Thorp Boardman, Joseph L. Bristow, Viscount James Bryce, Nicholas Murray Butler, Archibald Willingham Butt, Joseph Gurney Cannon, George B. Cortelyou, Charles Curtis, John A. Dix, Charles W. Fairbanks, John Hays Hammond, Myron T. Herrick, Charles Evans Hughes, Robert Underwood Johnson, Walter H. Johnson, Frank B. Kellogg, Philander C. Knox, Robert Todd Lincoln, Henry Cabot Lodge, William H. Moody, Francis G. Newlands, Charles Dyer Norton, John J. Pershing, Gifford Pinchot, Whitelaw Reid, Theodore Roosevelt, Elihu Root, J. S. Sherman, Henry Lewis Stimson, Nathan Straus, Oscar S. Straus, Robert A. Taft, Willis Van Devanter, Booker T. Washington, Edward Douglass White, George W. Wickersham, James Wilson, Woodrow Wilson, and Luke E. Wright.