In June 1843, Bishop Forbin-Janson created the Holy Childhood movement in France in order to train Christian children to be concerned about children in non-Christian countries. The movement spread rapidly and as of 1846, Canada began to be interested in it. But, after several good years, the Holy Childhood movement, little by little, lost some of its vitality.

In 1908, Delia introduced this children's missionary movement in her little school at Outremont, then she undertook to promote it in all the schools of the city. In 1917, the whole diocese of Montreal was entrusted to her. Eventually, most of the bishops of the Province of Quebec called upon Delia and her Congregation to revive the Holy Childhood which sows in the hearts of the youngsters and their teachers values of life, openness and commitment at all levels.