Founded by Mr. Frank Duff in Dublin in 1911, members of the Legion of Mary aspire to model Mary and carry out the mission of self-sanctification with prayers of Faith, Hope and Love. Witnessing the example of Mary our Heavenly Mother, Legionaries are not afraid of toil or hardship. Finally, Legionaries strive to spread the Word of God to the community.

There are two praesidia in our school, namely Mediatrix of All Graces Px. and Immaculate Heart of Mary Px.. We hold regular meetings every week to pray together and share experiences after weekly assignments. Assignments include religious book reading and service to others in need. Members regularly visit the 'Home of Love' in Sham Shui Po where they tutor children from new immigrant families. Legionaries also help the elderly in St. Mary’s Home for the Aged in Wong Chuk Hang and help deliver the free lunchboxes to the street sleepers around Yau Ma Tei and Mong Kok. During the Chinese New Year, the Legion also gets involved in evangelization work such as contacting visitors at the Flower Market in Victoria Park. Moreover, we keep close contact with Legionaries in other Catholic schools in Wanchai through joint school curia functions, including Acies, Annual Reunion, pilgrimage and retreat.