History of devotion
 The history of the devotion to the Heart of Mary is connected on many points with that to the Heart of Jesus. The attention of Christians was early attracted by the love and virtues of the Heart of Mary. The Gospels recount the prophesy delivered to her at Jesus' presentation at the temple: that her heart would be pierced with a sword. This image (the pierced heart) is the most popular representation of the Immaculate Heart. The Gospels further invited attention to Mary's heart with its depictions of Mary at the foot of the cross at Jesus' crucifixion. St. Augustine said of this that Mary was not merely passive at the foot of the cross; "she cooperated through charity in the work of our redemption".

Another Scriptural passage to help in bringing out the devotion was the twice-repeated saying of Saint Luke, that Mary kept all the sayings and doings of Jesus in her heart, that there she might ponder over them and live by them. A few of Mary's sayings, also recorded in the Gospel, particularly the Magnificat (the words Mary is reported to have said to describe the experience of being pregnant with Jesus), disclose new features in Marian psychology. Some of the Church Fathers also throw light upon the psychology of Mary, for instance, Saint Ambrose, when in his commentary on The Gospel of Luke he holds Mary up as the ideal of virginity, and Saint Ephrem, when he poetically sings of the coming of the Magi and the welcome accorded them by the humble mother. Some passages from other books in the Bible are interpreted as referring to Mary, in whom they personify wisdom and her gentle charms. Such are the texts in which wisdom is presented as the mother of lofty love, of fear, of knowledge, and of holy hope. In the New Testament Elizabeth proclaims Mary blessed because she has believed the words of the angel who announced that she would become pregnant with Jesus, although she was still a virgin; the Magnificat is an expression of her humility. In answering the woman of the people, who in order to exalt the son proclaimed the mother blessed, Jesus himself said: "Blessed rather are they that hear the word of God and keep it." The Church Fathers understood this as an invitation to seek in Mary that which had so endeared her to God and caused her to be selected as the mother of Jesus, and found in these words a new reason for praising Mary. St. Leo said that through faith and love she conceived her son spiritually, even before receiving him into her womb, and St. Augustine tells us that she was more blessed in having borne Christ in her heart than in having conceived him in the flesh.

It is only in the twelfth, or towards the end of the eleventh century, that slight indications of a regular devotion are perceived in a sermon by St. Bernard (De duodecim stellis), from which an extract has been taken by the Church and used in the Offices of the Compassion and of the Seven Dolours. Stronger evidences are discernible in the pious meditations on the Ave Maria and the Salve Regina, usually attributed either to St. Anselm of Lucca (d. 1080) or St. Bernard; and also in the large book "De laudibus B. Mariae Virginis" (Douai, 1625) by Richard de Saint-Laurent. Penitentiary of Rouen in the thirteenth century. In St. Mechtilde (d. 1298) and St. Gertrude (d. 1301) the devotion had two earnest adherents. A little earlier it had been included by St. Thomas Becket in the devotion to the joys and sorrows of Mary, by Blessed Hermann (d.1245), one of the first spiritual children of Saint Dominic, in his other devotions to Mary, and somewhat later it appeared in St. Bridget's "Book of Revelations". Johannes Tauler (d. 1361) beholds in Mary the model of a mystical, just as St. Ambrose perceived in her the model of a virginal soul. St. Bernardine of Siena (d.1444) was more absorbed in the contemplation of the virginal heart, and it is from him that the Church has borrowed the lessons of the Second Nocturn for the feast of the Heart of Mary. St. Francis de Salthis heart, the model of love for God, and dedicated to it his "Theotimus".

During this same period one finds occasional mention of devotional practices to the Heart of Mary, e.g. in the "Antidotarium" of Nicolas du Saussay (d.1488), in Julius II, and in the "Pharetra" of Lanspergius. In the second half of the sixteenth century and the first half of the seventeenth, ascetic authors dwelt upon this devotion at greater length. It was, however, reserved to Saint Jean Eudes (d. 1681) to propagate the devotion, to make it public, and to have a feast celebrated in honor of the Heart of Mary, first at Autumn in 1648 and afterwards in a number of French dioceses. He established several religious societies interested in upholding and promoting the devotion, of which his large book on the Coeur Admirable (Admirable Heart), published in 1681, resembles a summary. Jean Eudes' efforts to secure the approval of an Office and feast failed at Rome, but, notwithstanding this disappointment, the devotion to the Heart of Mary progressed. In 1699 Father Pinamonti (d. 1703) published in Italian a beautiful little work on the Holy Heart of Mary, and in 1725 Pere de Gallifet combined the cause of the Heart of Mary with that of the Heart of Jesus in order to obtain Rome's approbation of the two devotions and the institution of the two feasts. In 1729 his project was defeated, and in 1765 the two causes were separated, to assure the success of the principal one.

In 1799 Pius VI, then in captivity at Florence, granted the Bishop of Palermo the feast of the Most Pure Heart of Mary for some of the churches in his diocese. In 1805 Pius VII made a new concession, thanks to which the feast was soon widely observed. Such was the existing condition when a twofold movement, started in Paris, gave fresh impetus to the devotion. The two factors of this movement were first of all the revelation of the "miraculous medal" in 1830 and all the prodigies that followed, and then the establishment at Notre-Dame-des-Victoires of the Archconfraternity of the Immaculate Heart of Mary, Refuge of Sinners, which spread rapidly throughout the world and was the source of numberless alleged graces. On July 21, 1855, the Congregation of Rites finally approved the Office and Mass of the Most Pure Heart of Mary without, however, imposing them upon the Universal Church.

During the third apparition at Fatima, Portugal on July 13, 1917, the Blessed Virgin Mary said that "God wishes to establish in the world devotion to Her Immaculate Heart" in order to save souls from going into the fires of hell and to bring about world peace. She also asked for the consecration of Russia to Her Immaculate Heart. On March 25, 1984, Pope John Paul ll fulfilled Our Lady's request when he made the solemn act of consecration of the world and implicitly, Russia to the Immaculate Heart of Mary before the miraculous statue of Our Lady of Fatima brought to Saint Peter's Square in the Vatican for the momentous occasion. Sister Lucia, (then) the only surviving visionary of Fatima confirmed that the request of Our Lady for the consecration of Russia to the Immaculate Heart of Mary was accepted by Heaven and therefore, was fulfilled. Again on October 8, 2000, Pope John Paul made an act of entrustment of the world to Immaculate Heart of Mary for the new millenium.