The series contains textual records spanning the period 1908-1936 created by, collected by, or related to the immediate or extended McLennan family. This material might have been created and/or collected after the death of William McLennan, particularly by his son, William Durie McLennan, and does not appear to have been arranged by Hugh McLennan (1927-2004). Material includes correspondence, including a bound volume of World War I letters; histories of the MacLeod clan and William Stewart; and ephemera.

The series consists of photographs and textual records spanning the period 1850-1984, predominantly 1880-1960, relating to the McLennan family as arranged by Hugh McLennan (1927-2004). The series also comprises records related to Hugh McLennan's work as a camp counsellor north of Montreal during the early 1940s.

The series includes photographs; incoming and outgoing correspondence; genealogical and family information; diaries, including World War I diaries, and remembrances; newspaper clippings and ephemera; official documents, including wills and marriage certificates; obituaries and tributes; drafts of writings, research notes, and sketches; McLennan's coil-bound notebooks about canoe trips, a typescript of one of McLennan's camping journals and accompanying photographs; a letter to a family member regarding McLennan family genealogy; and photocopies of birth, marriage, and death notes in the family Bible. Family members prominently represented include Hugh McLennan (1825-1899), John Stewart McLennan (1853-1939), Francis McLennan (1857-1940), Bartlett McLennan (1868-1918), Isabella Christine McLennan (1870-1960), Hugh McLennan (1887-1915), and William McLennan (1856-1904).