On February 11, 2018, the Congregation for Divine Worship and the Discipline of the Sacraments inscribed a new obligatory Memorial of the Blessed Virgin Mary, Mother of the Church, into the General Roman Calendar. This memorial is celebrated every year on the Monday after Pentecost.

From the Common of the Blessed Virgin Mary, except for the following:

Office of Readings

Second Reading
From the Address of Pope Saint Paul VI, at the conclusion of the third session of the most holy Second Vatican Council
(November 21, 1964: AAS 56 [1964], 1015-1016)

Mary, Mother of the Church

Taking into consideration the close ties by which Mary and the Church are bound together, to the glory of the Blessed Virgin and for our consolation, We declare Mary Most Holy to be Mother of the Church, that is, of the whole Christian people, faithful and Pastors alike, who invoke her as their most loving Mother; and We establish that by this sweetest of names the whole Christian people should henceforth give still greater honor to the Mother of God and offer her their supplications.

Venerable Brothers, this concerns a title by no means new to Christian piety; indeed the Christian faithful and the universal Church choose to invoke Mary principally by the name of Mother. In truth, this name belongs to the genuine nature of devotion to Mary, since it rests firmly on that very dignity with which Mary is endowed as the Mother of the Incarnate Word of God.

Just as the Divine Motherhood is the basis both for Mary’s unique relationship with Christ and for her presence in the work of human salvation accomplished by Christ Jesus, so likewise, it is principally from the Divine Motherhood that the relationships which exist between Mary and the Church flow. Mary is indeed the Mother of Christ who, at the moment he assumed human nature in her virginal womb, joined to himself, as Head, his Mystical Body, which is the Church. Mary, therefore, as Mother of Christ, must also be regarded as Mother of all the faithful and Pastors alike, that is to say, of the Church.

Herein lies the reason why we, though unworthy and weak, yet in a spirit of trust and with ardent filial love, raise our eyes to her. She who once gave us Jesus, the fount of heavenly grace, cannot fail to offer her maternal help to the Church, especially at this time in which the Spouse of Christ strives with greater zeal to fulfil her salvific mission

These closest of bonds between our heavenly Mother and the human race urge Us, moreover, to foster and further strengthen this confidence. Even though she has been enriched with superabundant and wondrous gifts from God so as to be made worthy to be Mother of the Incarnate Word, nevertheless, Mary is very near to us. Like us, she is a child of Adam and so too our sister on account of our common human nature; she was preserved from the stain of original sin by reason of the future merits of Christ, but she added to these gifts received from on high the example of her own perfect faith and so merited the proclamation in the Gospel: “Blessed are you who have believed.”

In this mortal life she embodied the perfect form of a disciple of Christ, she was the mirror of all virtues, and in her manner of life exemplified fully those beatitudes proclaimed by Christ Jesus. Consequently, the universal Church, while she lives out the many facets of her life and in her active zeal, draws from the Virgin Mother of God the peerless example of how to imitate Christ perfectly.

Responsory
Cf. Luke 1:35

The Holy Spirit came down upon Mary:
— the Power of the Most High overshadowed her.

Once more it filled her, sharing in the Passion of her Son as the Mother of the redeemed:
— the Power of the Most High overshadowed her.

Prayer, as at Morning Prayer.

Morning Prayer

Canticle of Zechariah

Ant.   The disciples devoted themselves with one accord to prayer with Mary, the Mother of Jesus.

Prayer

O God, Father of mercies,
whose Only Begotten Son, as he hung upon the Cross,
chose the Blessed Virgin Mary, his Mother,
to be our Mother also,
grant, we pray, that with her loving help
your Church may be more fruitful day by day
and, exulting in the holiness of her children,
may draw to her embrace all the families of the peoples.
Through our Lord Jesus Christ, your Son,
who lives and reigns with you in the unity of the Holy Spirit,
God, for ever and ever.

Evening Prayer

Canticle of Mary

Ant.   The Lord said to his mother: Woman, behold your son. And to the disciple: Behold your mother.

Prayer, as at Morning Prayer.

You may find more information at the USCCB Website.