Correspondence, letterbooks, journals, drafts of articles and books, speeches and lectures, biographical and genealogical data, business papers, legal and financial papers, scrapbooks, printed material, maps, drawings, and other papers encompassing Olmsted's career and private life.

The papers focus on Olmsted's career as a landscape architect, specifically as a designer of parks and the grounds of private estates and public buildings and as a city and regional planner. Includes material pertaining to his designs chiefly of Central Park in New York, N.Y., of the area surrounding Niagara Falls, N.Y., of the U.S. Capitol grounds, Washington, D.C., and of the grounds of the World's Columbian Exposition, Chicago, Ill., 1893. Material pertains, in part, to work undertaken by Olmsted and the firms of Olmsted and Vaux (1858), Frederick Law Olmsted (1858-1884), F.L. and J.C. Olmsted (1884-1889), F.L. Olmsted and Company (1889-1893), Olmsted, Olmsted, and Eliot (1893-1897), F.L. and J.C. Olmsted (1897-1898), and Olmsted Brothers (1898-1961). Also documents Olmsted's writings, his investigation of slavery in the South (1850s), his role as general secretary of the U.S. Sanitary Commission during the Civil War, and his work as superintendent of John C. Frémont's gold mining estates in Mariposa, Calif.

Olmsted family papers include a journal and other papers of Gideon Olmsted documenting his adventures as a privateer during the Revolutionary war; journals kept by Frederick Law Olmsted's father, John, recording activities of the Olmsted family as well as local and national events; and correspondence of John Olmsted (father), John Hull Olmsted (brother), Frederick Law Olmsted, Jr. (son), and John Charles Olmsted (nephew).

Correspondents include Henry W. Bellows, Samuel Bowles, Charles Loring Brace, Daniel Hudson Burnham, H. W. S. Cleveland, George William Curtis, Charles A. Dana, Edwin Lawrence Godkin, A. H. Green, Edward Everett Hale, William James, Clarence King, Frederick John Kingsbury, Frederick Newman Knapp, Charles Follen McKim, Charles Eliot Norton, Whitelaw Reid, H. H. Richardson, Charles N. Riotte, Carl Schurz, George Templeton Strong, George Washington Vanderbilt, Calvert Vaux, Henry Villard, George E. Waring, Jr., and Katherine Prescott Wormeley.