Correspondence, memoranda, speeches, press releases, clippings, printed matter, photographs, and memorabilia documenting Hilles' activities as secretary to President Taft (1911-1913), as chairman and committeeman to the Republican National Committee (1912-1937) and as Assistant Secretary of the Treasury (1909-1911). His correspondence as Taft's secretary is of special importance as being originally part of the President's office files. His work as administrator of the Ohio Industrial School (1892-1902) and the New York Juvenile Asylum (1902-1909) is also documented in the correspondence. Family correspondence is particularly rich for the fall of 1911 when Hilles was touring the country with President Taft, and for 1912 just before his appointment as chairman of the Republican National Committee. Correspondents of note include Charles Francis Adams, William Jennings Bryan, Nicholas Murray Butler, Andrew Carnegie, Josephus Daniels, Charles G. Dawes, Theodore Dreiser, Henry W. Farnam, Irving Fisher, Arthur T. Hadley, Warren G. Harding, Charles Evans Hughes, Frank B. Kellogg, Henry Cabot Lodge, Gifford Pinchot, Theodore Roosevelt, Elihu Root, Henry L. Stimson, Cornelius Vanderbilt, Booker T. Washington and George Westinghouse.