Most of Lighthall's varied interests and activities are represented in his papers which fall into a number of series. There is a general series of letters and papers 1875-1954 which includes much but not all of the correspondence. There are letters from many Canadian literary figures (before ca 1940) including Duncan Campbell Scott, Charles Sangster, Charles G.D. Roberts, W.W. Campbell and Stephen Leacock. Others represented in this series include Sir Wilfrid Laurier and Sir William Van Horne (about his and Lighthall's collections of pictures). Among the subjects covered are the McCord Museum, the Chateau de Ramezay, the McGill University Library, the Manitoba School question, conscription and imperial government. There are series for the Canadian Author's Association, the Canadian Union of Municipalities, the Metropolitain 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 Captain MacKenzie Forbes' files from the Military Hospitals Commission, 1917. 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 a large series of documents, both originals and copies dealing the region of Huntingdon, Chateauguay and Beauharnois. 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 as well Lighthall's index of Canadian author's pseudonyms (ca 1880-ca 1900). In addition to this manuscript material, there is the Lighthall collection of books which contains some three hundred volumes of metaphysics, history and poetry many of which are either inscribed to W.D.L. or contain his annotations.