Correspondence, letterbooks, memoranda, drafts of speeches and articles, reports, subject files, legal records, newspaper clippings, printed material, and other papers relating primarily to Olney's activities as U.S. attorney general and secretary of state during Grover Cleveland's presidential administration. Also includes material pertaining to his Boston, Mass., law practice. Subjects include pre-World War I American foreign policy; canal through Nicaragua or Panama; Democratic Party politics; the 1895 Cuban revolution; farmers' protest and labor strife following the Depression of 1893; the proposed arbitration treaty with Great Britain; difficulties with Great Britain over the Bering Sea fisheries dispute and Venezuela-British Guiana boundary dispute; the landmark court decisions of the 1890's; insurrections in the Philippines during the Philippine American War, 1899-1902; the Pullman Strike of 1894; railroads especially the Boston and Maine Railroad, Northern Pacific Railway Company, and Southern Pacific Company; Sherman Anti-Trust Act; Silver Purchase Act of 1894; and trade-unions. Also includes research files collected by Olney's biographer, Henry James (1879-1947).

Correspondents include Alvey A. Adee, Edwin Farnsworth Atkins, Clara Barton, Thomas F. Bayard, French Ensor Chadwick, Grover Cleveland, Josephus Daniels, Enrique Dupuy de Lôme, Charles William Eliot, Samuel Gompers, Walter Quintin Gresham, Benjamin Harrison, John Hay, George Frisbie Hoar, Daniel Scott Lamont, Robert Lansing, Henry Cabot Lodge, S.S. McClure, William McKinley, Peter B. Olney, Walter Hines Page, Baron Julian Pauncefote, Robert A. Pinkerton, James Roosevelt Roosevelt, Theodore Roosevelt, James Brown Scott, George W. Smalley, Ida M. Tarbell, Booker T. Washington, Henry White, and Woodrow Wilson.