The Legion of Mary (Latin: Legio Mariae) is an international association of practicing members of the Catholic Church who serve the Church on a voluntary basis. It was founded in Dublin, Ireland, as a Roman Catholic Marian Movement by layman Br. Frank Duff. Today, between active and auxiliary (praying) members there are over 10 million members worldwide, making it the largest apostolic organization of lay people in the Catholic Church. Membership is highest in South Korea, Philippines, Brazil, Argentina and the Democratic Republic of Congo. These countries have between 250,000 and 500,000 members each.

To be in the Legion of Mary, one must be a lay catholic. The stated mission is for active members to serve God under the banner of Mary by practicing the Corporal and spiritual Works of Mercy as mentioned in chapter 33 of the Legion of Mary Handbook. The main apostolate of the Legion consists in activities directed towards Catholics and non-Catholics encouraging them in their faith or inviting them to become Catholic. This is done through encouraging them in prayer, attending Mass and learning more about the Catholic faith. The members of the Legion are primarily engaged in the performance of the Spiritual Works of Mercy rather than works of material aid.

The Legion of Mary at OLPH meets every Tuesday at 6:30 pm. For more information on how to join, please contact legion@olphrm.org.