According to a Brief of Pope Pius XI dated December 18, 1926, the members of the Militia Immaculatae can obtain a plenary indulgence on the following days:
— the day of their enrollment in the MI;
— the anniversary of the founding of the MI (October 17);
— the Feast of the Immaculate Conception (December 8);
— the Feast of the Annunciation (March 25);
— the Feast of Our Lady of Lourdes (February 11);
— the anniversary of the first appearance of Our Lady in Fatima (May 13);
— the Feast of St. Francis of Assisi (October 4);
— the Feast of Our Lady of the Miraculous Medal (November 27).
Besides the usual conditions for receiving a plenary indulgence (sacramental Confession within eight days, reception of Holy Communion, prayer for the intentions of the Popes, freedom from attachment to any sin), one must renew his promise to adhere to the Statues of the MI and to keep them faithfully.