 In the term of the first principal, Sr Mary Donatres Egan RSJ, the demand for Catholic education in North Sydney grew to the point where the school extended to educate from primary to secondary education which included the building of a new school on the Mount St property the school originated on.This new school specialised in commercial subjects; cooking, domestic Science and dressmaking.In 1955 when the Archbishop of Sydney established an Education Office, both the Mount St Commercial and Domestic Science School and Ridge St's “Practice and Demonstration” school of St Joseph's Training School combined.