1. Immaculate Conception (December 8), solemnity: "Joint celebration of the Immaculate Conception of Mary, of the basic preparation for the coming of the Saviour, and of the happy beginning of the Church without spot or wrinkle" (Marialis Cultus** or MC,3)
2. Fourth Sunday of Advent: "It recalls the ancient prophecies concerning the Virgin Mother and the Messiah and includes readings from the Gospel concerning the imminent birth of Christ and His Precursor. (MC 3)
3. Mary Mother of God (January 1), solemnity: Celebrates "the part played by Mary in the mystery of salvation," exalts "the singular dignity which this mystery brings to the 'holy Mother,'" renews adoration to the newborn Prince of Peace," and implores from God, through Mary's intercession, "the supreme gift of peace" (MC 5).
4. Presentation of the Lord (February 2), feast: "Joint commemoration of the Son and of the Mother," that is, "a celebration of a mystery of salvation accomplished by Christ, a mystery with which the Blessed Virgin was intimately associated as the Mother of the Suffering Servant of Yajweh, as the one who performs a mission belonging to ancient Israel, and as the model for the new people of God, which is ever being tested in its faith and hope by suffering and persecution" (MC 7)
5. Our Lay of Lourdes (February 11), optional memorial.
6. Annunciation of the Lord (March 25), solemnity: "A joint feast of Christ and of the Blessed Virgin: of the Word, who becomes 'Son of Mary' (Mk 6:3), and of the Virgin, who becomes Mother of God" (MC 6)
7. Our Lady Mediatrix of All Grace (May 8), optional memorial (local celebration).
8. Visitation (May 31), feast: "The Liturgy recalls the Blessed Virgin Mary carrying her Son within her, and visiting Elizabeth to offer charitable assistance and to proclaim the mercy of God the Savior" (MC 7)
9. Immaculate Heart of Mary (Saturday after the Solemnity of the Sacred Heart of Jesus), optional memorial: It expresses "tendencies which have emerged in contemporary devotion" (MC 8).
10. Our Lady of Mount Carmel (July 16), optional memorial: "Originally celebrated by a particular religious family, but … today, by reason of the popularity [it has] gained, it can truly be considered ecclesial" (MC8).
11. Dedication of Saint Mary Major (August 5), optional memorial
12. Assumption (August 15), solemnity: "It is the feast of [Mary's} destiny of fullness and blessedness, of the glorification of her immaculate soul and of her virginal body, of her perfect configuration to the Risen Christ; a feast that sets before the eyes of the Church and of all mankind the image and the consoling proof of the fulfillment of their final hope." (MC6)
13. Queenship of Mary (August 22), memorial: "The Solemnity of the Assumption is prolonged in the celebration of the Queenship of the Blessed Virgin Mary, which occurs seven days later. On this occasion we contemplate her who, seated beside the King of Ages, shines forth as Queen and intercedes as Mother" (MC6).
14. Birth of Mary (September 8), feast. It commemorates a salvific event: "Mary the hope of the entire world and the dawn of salvation" (MC 7).
15. Our Lady of Sorrows (September 15), memorial: "A fitting occasion for reliving a decisive moment in the History of Salvation and for venerating, together with the Son lifted up on the Cross, His suffering Mother" (MC 7)
16. Our Lady of the Rosary (October 7), memorial: A truly "ecclesial" celebration (MC 8)
17. Mary, Mother of the Church (October 11), optional memorial (local celebration).
18. Presentation of Mary (November 21), memorial. It proposes a "lofty and exemplary" value and carries on a venerable tradition "having" [its] origin especially in the East" (MC 8).
19. Our Lady of the Miraculous Medal (November 27), optional memorial (local celebration).
20. Our Lady of Guadalupe (December 12), memorial: A commemoration "connected with local devotions" which has "acquired a wider popularity and interest" (MC 8)

* This list here is taken from Dictionary of Mary (New York: Catholic Book Publishing Co., 1985) pp.387-392.

** In 1974, "Pope Paul VI issues the Apostolic Constitution Marialis Cultus which treats at length of liturgical Marian piety, popular Marian devotion, indicates the criteria for deciding which Marian practices are completely valid and for introducing new ones, and concludes with the theological and pastoral value of devotion to Mary." (Dictionary of Mary, p.416)