Materials include family papers from three families, the Breithaupt family, the Hewetson family, and the Clark family; records from the Guild of All Arts in Scarborough, Ontario, founded by Rosa Breithaupt Hewetson Clark and Spencer Clark; and several smaller collections acquired by the Breithaupt family and by Spencer Clark. The personal library of Spencer Clark, which includes many books, periodicals, government documents, and ephemeral items, was donated together with the archival collections, and is particularly strong in the fields of urban planning, architecture, and Canadian art.