Fonds illustrates Madeleine Boss Lasserre’s career and interests as a music educator of children and adults in Toronto, Ontario. Most of the material was created between 1925 and 1977, while Lasserre was actively employed with the Margaret Eaton School and the Toronto Conservatory of Music. A small subset of the records were created outside of this time span. Records include: Dalcroze teaching and demonstration notes and diagrams; correspondence with colleagues and students; material pertaining to general early childhood education; and material related to the administration and promotion of courses in Dalcroze Eurhythmics. Fonds contains notes and notebooks, pamphlets, programmes, correspondence, clippings and scrapbooks, as well as photographs of Lasserre and other members of the Dalcroze and music communities.