Seventy-one notebooks with handwritten drafts of a wide variety of works make up a large portion of the Osbert Sitwell Collection, along with galley files and typescripts of additional titles, and an extensive assortment of correspondence. The collection is arranged in five series: Series I. Works, 1898-1965 (28 boxes); Series II. Correspondence, 1902-1969 (12.5 boxes); Series III. Personal Papers, 1898-1969 (.5 boxes); Series IV. David Horner, 1932-1966 (2.5 boxes); and Series V. Third Party Works and Correspondence, 1887-1969 (1.5 boxes). Portions of this collection were previously accessible through a card catalog, but have been re-cataloged as part of a retrospective conversion project to include new accessions.

The Works series is composed of page and galley proofs for all five volumes of Sitwell's autobiography, . Holograph and typescript drafts of the collected essays of are present, as are drafts of , , and These works are arranged alphabetically by title. The seventy-one notebooks which comprise the rest of the works series contain drafts of many of Sitwell's notable works, individual poems, and draft letters. Not all of the materials in these notebooks have been indentified, nor are they arranged chronologically. All identified titles, including those in the notebooks, are listed in the Index of Works at the end of this guide.

The Correspondence Series is arranged in two sections, outgoing mail by Sitwell and incoming letters to Sitwell. Of particular note are nearly a thousand letters from Sitwell to his companion David Horner, written between 1926 and 1964. A small batch of letters to Horner, written between 1951 and 1956, arrived in a later accession and are group together at the end of the Horner section. There are smaller batches of letters to and from Lorna Andrade, Richard Grants, Edith and Sacheverell Sitwell, and others. Correspondents in this series are listed in the Index of Correspondents at the end of this guide.

The small Personal Papers Series comprises bank and royalty records, legal documents, lists, and Sitwell family photographs. The David Horner Series contains letters primarily to Horner from various friends and acquaintances. Leslie Hartley and Edith Sitwell are well represented in this series. All correspondents in the David Horner Series are listed in the Index of Correspondents at the end of this guide.

The Third-Party Works and Correspondence Series holds works by Sitwellian scholars and friends as well as correspondence between his friends and business associates. Galley proofs of Richard Fifoot's bibliography of Edith Sitwell's work are present, in addition to poems by Sacheverell Sitwell and a holograph draft of Max Wykes-Joyce's . Also of note is a pen and ink sketch of Sitwell by Peter Roseland, lists and materials for Sitwell's poetry reading tour in America, and letters and documents regarding Ida Sitwell's scandal-laden bankruptcy. All identified titles in this series are listed in the Index of Works and all the correspondents are listed in the Index of Correspondents at the end of this guide.

Elsewhere in the Ransom Center are 25 photographs of Sitwell, his family, friends, and images of Rennishaw Hall, located in the Literary Files of the Photography Collection. Also present are 26 vertical files containing newspaper clippings covering the publication and criticism of Sitwell's works as well as biographical and printed material. Portraits of Sitwell appear in two collections in the Art Collection as well as several items from his own art collection, one folder of newspaper clippings is located in the Scrapbook Collection, and one reel-to-reel recording of an interview with Sitwell in the Sound Recordings Collection. Other materials related to Osbert Sitwell may be found in the following manuscript collections at the Ransom Center: Adams, James Donald Barker, George Bermondsey Book Betjeman, John Blunden, Edmund Charles Brooke, Jocelyn Connolly, Cyril Coppard, Alfred Edgar Cunard, Nancy Duncan, Ronald Frederick Henry Ervine, St. John Greer Garnett, David Garvin, J. L. Golden Cockerel Press Hutchinson, Mary La Farge, Oliver Lehmann, John Lewis, Sinclair Lindsay, Philip Lowndes, Marie Adelaide (Belloc) MacKenzie, Compton MacNamara, Brinsley Masefield, John Nehls, Edward PEN Richards, Grant Sassoon, Siegfried Lorraine Shaw, George Bernard Sitwell, Edith, Dame Smith, L. P. Strong, Leonard Alfred George Tchelitchew, Pavel Tyler, Parker Walpole, Hugh, Sir Waugh, Alec Webb, Stella Dorothea Welch, Denton