"Mary, Mediatrix of all graces" is a title that some give to Mary the mother of Jesus, in line with a belief that all the graces that her son gives come through her.
In 1896, French Jesuit priest René-Marie de la Brosse published a proposal that the Pope should make a dogmatic definition about the role of Mary in the distribution of all graces, but did not require that it be in the form of declaring her to be the mediatrix of all graces.[1] Eight years later, Belgian Redemptorist priest François Xavier Godts wrote a book proposing precisely that it be defined that Mary is the mediatrix of all graces. Désiré-Joseph Mercier, Cardinal Archbishop of Mechelen, Belgium championed this cause. In 1921, Pope Benedict XV, responding to petitions from Belgium, including one signed by all its bishops, established the annual celebration in that country of a feast day of Mary Mediatrix of All Graces.[1] In printings of the Roman Missal from that date until 1961, the Mass of Mary Mediatrix of All Graces is found in the appendix Missae pro aliquibus locis (Masses for Some Places), but not in the general calendar for use wherever the Roman Rite is celebrated.[2] Other Masses authorized for celebration in different places on the same day 31 May were those of the Blessed Virgin Mary Queen of All Saints and Mother of Fair Love and Our Lady of the Sacred Heart of Jesus.
The Second Vatican Council referred in its document Lumen Gentium to Mary as "Advocate, Auxiliatrix, Adjutrix and Mediatrix". Some interpret this last word as referring not to some of the graces that Jesus has given and gives but to all of them.[3]
On the meaning of "mediatrix", see the article Mediatrix.