The Legion of Mary is an association of Catholic laity who serve the Church on a voluntary basis. It was founded in Dublin, Ireland as a Roman Catholic Marian Movement by a layman, Frank Duff, and today has over three million active members worldwide. The number of auxiliary members is estimated to be about ten million.
To be in the Legion of Mary, one must be a practicing Catholic. Active members serve God under the banner of Our Lady by practicing the Spiritual Works of Mercy. The main apostolate of the Legion consists in activities directed toward all men and women, young and old, rich and poor, as well as people from the margins of society (homeless, prostitutes, prisoners, etc.) and toward non-Catholics. The members of the Legion of Mary are primarily engaged in the performance of Spiritual Works of Mercy rather than works of material aid.