Fonds consists of three series: diaries recorded in bound journals kept by Mackenzie during his adolescence and adult life; manuscripts of three works of non-fiction; and photo albums and passports of his family,and his life and travels overseas. Mackenzie recorded extensively on local and international political and social events. In his youth, Mackenzie was preoccupied with fascist and socialist movements in Europe. In later life, he became concerned with the influence of American foreign policy and its impact on Canadian sovereignty. His diaries also reflect his interest in films and the theatre, with entries on the deaths of his favourite actors and actresses and frequent entries on the various films and plays he attended in Toronto and abroad. He also wrote about the tours and activities of various royal families, and chronicled his own travels throughout the world in detail, including his extended stays in Australia and England. Mackenzie kept meticulous notes on his employment history and living environment. He also recorded details of his writing activities and his efforts to publish and support himself through writing. Mackenzie kept entries on his social activities in the gay community of Toronto, his relationships with other men, and later in life, his reflections on gay marriage, same-sex legal rights, the AIDS crisis, and the rights of gay couples to adopt and raise children.