The papers of W.D. Lighthall are divided into a number of different series: an Original Series, Letters and Papers, 1881-1946, and a New Series, Letters and Papers, 1865-1954. The greater part of the correspondence is to be found in these two series. Correspondents include the following Canadian literary figures: Duncan Campbell Scott, Charles Sangster, Charles G.D. Roberts, W.W. Campbell and Stephen Leacock. Other represented in these series are Sir Wilfrid Laurier on political questions and Sir William Van Horne on artistic ones. Among other subjects covered are the McCord Museum, the Château de Ramezay, the McGill University Library, the Manitoba school question, conscription and imperial government.

There are series for the Canadian Authors' Association, the Metropolitan Parks Commission, the Great War Veterans' Association and the Royal Society of Canada. The papers of the Montreal Armenian Relief Committee (1920s) are included, as are the papers of secretary, George S. Wilson, of the Society of Canadian Literature, 1889-1890. There is some material on various legal cases in which Lighthall was involved including some Indian land claims. There is a series of personal financial records and some material on church union (ca. 1910). There is also a long series of documents, both originals and copies, dealing with the region of Huntingdon, Chateauguay and Beauharnois, Quebec. Most of Lighthall's literary works are represented in draft and / or annotated form including The False Chevalier (1898) and The Master of Life (1908). There is also Lighthall's index of Canadian authors' pseudonyms (ca. 1880- ca. 1900). Finally, the papers include the dossier of eighteenth-century documents on which Lighthall based his romance The False Chevalier. Among these is a transcription of extracts from the diary of Michel Chartier de Lotbinière (1723-1798).

In addition to this manuscript material, there is the Lighthall Special Collection of books. This collection contains some five hundred titles of works, including reprints, on metaphysics, history and Canadian poetry. Many contain Lighthall's annotations; others are inscribed to him by the author.