The Legion of Mary is an international association of members of the Catholic Church who serve it on a voluntary basis. It was founded in Dublin, as a Marian movement by the layman and civil servant Frank Duff.

Catholic Marian movements and societies have developed from the veneration of the Blessed Virgin Mary by members of the Catholic Church. These societies form part of the fabric of Mariology in the Catholic Church. Popular membership in Marian organizations grew significantly in the 20th century, as apparitions such as Our Lady of Fátima gave rise to societies with millions of members, and today many Marian societies exist around the world. This article reviews the major Marian movements and organizations.