Fonds comprises Ronald St. John Macdonald's records regarding his personal, academic, and professional activities as a jurist, judge, and professor. Records include those related to Macdonald's involvement with Osgoode Hall, University of Western Ontario, University of Toronto, Dalhousie University, the European Court of Human Rights, the Hague, Peking University, World Academy of Arts and Science, Canadian Council of International Law, United Nations, Institute of International Law, African Society of International Law, British Institute of International Law, Canadian Institute of International Law, International Law Association, and others. Records types include correspondence; meeting minutes and agendas; research materials; photographs; newsletters; newspaper clippings; manuscripts; and off-prints.

File includes a postcard with a black and white photograph of Pietro Mascagni (1863-1945), an Italian opera composer. The postcard has various signatures on the front, including Francesco Marconi (1855-1916, operatic tenor from Rome) and four other illegible signatures. The postcard is addressed to Frau Dr. Lehnsern(?) of Berlin. File also includes the incipits of three pieces by Ignaz Moscheles (1794-1870), signed at dated October 3, 1844. There are also five letters written by the following composers: Jacques Offenbach (1879), Gustav Mahler (1899), Edvard Grieg (1902), Maurice Ravel (1921), and Ignacy Paderewski (n.d., 1860-1941).