Designed by the Blessed Virgin Herself
When our Blessed Mother gave the design of the Medal to Saint Catherine Labouré she said, “Have a medal struck upon this model. Those who wear it will receive great graces, especially if they wear it around the neck.” And, “Now it must be given to the whole world and to every person.” With approval of the Church, the first Medals were made in 1832 and were distributed in Paris. Almost immediately, the blessings and favors that Mary had promised began to shower down on those who wore her Medal, and it was called Miraculous by the people because of the many remarkable favors that they believed happened through divine mediation.
Origins of the Association
In order to spread devotion to Mary as Our Lady of the Miraculous Medal, an association was formed shortly after the first medals were distributed. The Association was established at the motherhouse of the Congregation of the Mission in Paris. (In appearing to Saint Catherine, a Daughter of Charity, Mary entrusted to the Daughters of Charity and the priests of the Congregation of the Mission the work of spreading this devotion to her through her medal.)
Spread of the Association; Official Approval by Pope Pius X
Gradually, other associations were established elsewhere in the world. Pope Pius X recognized these associations in 1905 and approved a charter in 1909.
From the Pontifical Approbation of 1905, Article 2:
The Association has as its end to attributing to the Virgin Mary, conceived without original sin, the honor that is due her; achieving their own sanctification, and exercising its apostolate, both of which the Holy Medal challenges and helps as much for the symbolism it shows as by virtue of those who wear it.