On October 7, Pope Francis inscribed the optional memorial of Our Lady of Loreto into the General Roman Calendar; this celebration will be observed on December 10. While proper liturgical texts will have to be translated into English and Spanish before receiving the requisite approval for liturgical use, what follows is a listing of interim liturgical guidelines for the celebration of this memorial:

Roman Missal

The Collect prayer for the new celebration is identical to one already found in the Roman Missal in the Common of the Blessed Virgin Mary: II. In Advent, Second Option. The remainder of the formulary – Prayer over the Offerings, Preface, Prayer after Communion, and Entrance and Communion Antiphons – can be drawn from the same Mass formulary as the Collect. White vestments are worn.

Lectionary for Mass

Aside from the usual Mass readings of the day, any Lectionary readings from the Common of the Blessed Virgin Mary may be used for Our Lady of Loreto. The following readings are also recommended by the Holy See (with citations from nos. 707-712 of the Lectionary for Mass):

First Reading

Isaiah 7:10-14; 8:10 (no. 707-7)

The virgin shall conceive and bear a son.

Responsorial Psalm

Luke 1:46-47, 48-49, 50-51, 52-53, 54-55 (no. 709-5)

R. The Almighty has done great things for me, and holy is his Name.

or: R. O Blessed Virgin Mary, you carried the Son of the eternal Father.

Gospel Acclamation

See Luke 1:28 (no. 711-1) 

Hail, Mary, full of grace, the Lord is with you; blessed are you among women.

Gospel

Luke 1:26-38 (no. 712-4)

Behold, you will conceive in your womb and bear a son.

Liturgy of the Hours

The Office of Readings, Morning Prayer, and Evening Prayer should observe the psalmody of the day. Other elements may be taken from either the psalter of the day or the Common of the Blessed Virgin Mary. The concluding prayer is from the Collect at Mass (see above). 

On this day, parishes may also wish to recite the famous Litany of Our Lady of Loreto, which is available at the following link.