The object of the Legion of Mary is the glory of God through the holiness of its members developed by prayer and active co-operation, under ecclesiastical guidance, in Mary's and the Church's work of crushing the head of the serpent and advancing the reign of Christ. Membership is open to those who belong to the Catholic Church and believe in its teaching. Its stated mission is for active members to serve God under the banner of Mary by the corporal and spiritual works of Mercy.