Holy Cross Catholic School had its modest beginnings in 1928 in a one room portable on Mortimer Avenue in East York with 46 pupils. The actual street address was 380 Mortimer Avenue. The original one-storey brick schoolhouse, which used an estimated 55,000 bricks and 6,200 floor tiles, had its official opening on April 12, 1944. The building consisted of four classrooms, office and two cloakrooms; an auditorium and two teachers’ lunch rooms were on the basement level. The new address was 299A Donlands Avenue beside Holy Cross Church.

An addition was made in 1948. This second-storey consisted of four classrooms, a lunchroom for the lay teachers, a nurse’s office, a sewing room, and a sitting room. The two classes that had been in the auditorium were moved upstairs.

In 1949, a Kindergarten-primary class was begun. In 1954, on November 22nd, a new portable was opened on the school property to accommodate twenty-seven Grade 3 pupils. By 1961, there were 4 portables on the property.

On January 23, 1963, the Toronto Metropolitan Separate School Board received tentative approval for the addition of ten classrooms (replacement of four) at a proposed cost of $200,000 and excavations began during the Easter holiday period.

In September of 1963, school opened with an enrolment of 635 students and a staff of twenty-one teachers. Construction of the new wing was not yet completed. In October, eight classes moved into the new addition, but the basement rooms weren’t yet ready and teachers had to make do, since no teachers’ desks or chairs had arrived. 

An Open House and Blessing of the new wing by Father Miller was held on Sunday, March 1st, 1964. But construction was not quite finished! In June of 1966, plans were submitted for the “Phase 2 Addition” to the school, which was to include two more classrooms, a library and a general purpose room. The budget was $125,000. The Government of Ontario gave the School Board a grant of $80,000 towards the cost. The addition was completed in 1967.