December 12 commemorates the apparition of Mary to Juan Diego, a Mexican peasant on the hill called Tepeyac. The Basilica of Our Lady of Guadalupe was erected near the spot where two apparitions of the Virgin are said to have appeared to an Indian convert Juan Diego in December 1531. In the second apparition, Juan Diego wanted to evade the Virgin as he was arriving near the place where he was supposed to meet our Lady. He decided to take a different route as he was running for help to save his uncle who was dying.  She appeared to him and asked "where are you going?" Full of shame he responded, and the Virgin said, "do not worry, your uncle is not dying and is well."

He then asked for a sign for the bishop, and she ordered Juan Diego to pick some of the flowers, during the winter, where he then brought them in his cloak to the bishop. When he opened his cloak, the flowers fell out and an image of the Blessed Mother was imprinted on it. This image became known as the Virgin of Guadalupe and all these events did much to accelerate the conversion of the Indians of Mexico to Christianity.

Pope Pius XI proclaimed her as "Patron of all Latin America" and it was then extended to the Philippine Islands by Pope Pius XII to "Empress of the Americas and the Philippines."