The papers of William Wilson Corcoran (1798-1888) span the years 1791-1896, with the bulk dated between 1849 and Corcoran's death in 1888. While the collection consists mostly of correspondence, it also contains financial records, newspaper clippings, printed materials, admission and calling cards, military commissions, notebooks, lists, and memorabilia. The papers further include a small number of letters and financial records of Corcoran's father, Thomas, and are organized into the following series: Family Correspondence , Incoming Letters , Outgoing Letters , Special Correspondence , Financial Records , and Miscellany .

Corcoran's career was distinguished by several features: his success as a financier dealing primarily in government securities; the extent of the property holdings he accumulated; the prominence of his many political, business, and social connections, which included presidents of the Unites States, senators, generals, and several of the leading businessmen of his day; the diverse philanthropic activities that especially marked the thirty-four years following his withdrawal from the firm of Corcoran & Riggs; and his lengthy tenure as one of Washington’s most prominent citizens.

The collection reflects Corcoran's career in several respects, none more so than his extensive connections with individuals in politics, business, and other fields. More than 125 correspondents in the collection are listed in the Dictionary of American Biography. Especially important is the Incoming Letters series, which includes many personal letters, often candid and sometimes lengthy, from prominent friends. These associations are also reflected in the lists of Corcoran's "dinner company" which can be found in the Miscellany series.

The Outgoing Letters series, which forms the largest part of the collection, consists mostly of letterpress copies of Corcoran's business correspondence. Written by Corcoran, Anthony Hyde, Corcoran's secretary for many years, and Arthur Brice, who assisted Corcoran and Hyde during Corcoran's last years, the letters deal mainly with Corcoran's management of his real and personal property holdings during the last half of his life. These letters are for the most part brief and impersonal, the main exception being the long and newsworthy letters that Anthony Hyde wrote Corcoran while the latter was traveling. Interspersed among these outgoing letters are many financial accounts and statements of stock holdings, rents collected, and other business and financial matters.

Common topics in the outgoing business letters are the execution of land and security transactions, payment of land taxes and property insurance, and the collection of rents, interest, and dividends. Correspondents are frequently Corcoran's agents-in-the-field or the banking and brokerage firms through which he operated, such as Riggs and Co. of New York, the Bank of America, and Wilson, Colston and Co. of Baltimore. Among the more frequently mentioned investment ventures are the Chesapeake and Ohio Canal Company; the Little Miami Railroad; the Philadelphia, Wilmington, and Baltimore Rail Road Company; the Baltimore and Ohio Railroad Company; California and Texas debts; the "Great Superior Scheme" in Wisconsin; Dubuque, Iowa, bonds; and Corcoran's Mississippi land holdings. While Outgoing Letters reflect Corcoran's business activities after 1845, letters and other records in the Incoming Letters and Financial Records series document his business and financial interests prior to that date.

Philanthropic and community activities, as reflected in Outgoing Letters, begin to appear with increasing frequency in the 1870s and are concerned with business and administrative operations such as sending checks to asylums, building the Corcoran Art Gallery, and informing women of admission procedures for Louise Home. In both Incoming Letters and Outgoing Letters the great preponderance of the philanthropically related correspondence deals with individuals who, beginning in the 1850s, sought charitable loans and donations from Corcoran as well as help in procuring jobs with the federal government. Corcoran acceded to some of these requests, getting in return many thank-you letters, but the number of requests became overwhelming after the Civil War. Anthony Hyde answered hundreds of these letters in the negative, and eventually developed a printed form letter for the purpose.

Although Corcoran's family life was marked by tragedy because of the early deaths of his wife and children, the Family Correspondence reflects mostly the happier moments. Especially prominent is Corcoran's intimate correspondence with his wife, Louise Amory Morris, during the five years between their courtship and her death.

Among the more notable figures whose correspondence appears in the collection with some frequency are statesmen and politicians William Aiken, John C. Breckinridge, Jesse D. Bright, James Buchanan, Leslie Combs, Jefferson Davis, John Wesley Davis, Daniel S. Dickinson, Stephen A. Douglas, Edward Everett, Millard Fillmore, Friedrich Karl Joseph von Gerolt, Ransom H. Gillet, R. M. T. Hunter, Robert Ward Johnson, George Wallace Jones, Amos Kendall, J. M. Mason, Aaron Vail, Robert J. Walker, Daniel Webster, and Robert C. Winthrop; businessmen and entrepreneurs August Belmont, Thomas Green Clemson, Junius Spencer Morgan, George Peabody, Elisha Riggs, Jr., and Lawrason Riggs; lawyer David Rorer; military officers John Lane Gardner and Robert E. Lee; authors and editors George Bancroft, John W. Forney, Gabriel Harrison, J. William Jones, Charles Lanman, the reverend Philip Slaughter, and James Grant Wilson; educators Edward Miner Gallaudet and Charles S. Venable; scientists Joseph Henry and Alexander von Humboldt; sculptors Alexander Doyle, Moses Jacob Ezekiel, and William Wetmore Story; and architect James Renwick, Jr.