The celebration of Easter is prolonged throughout the Easter season. The fifty days from Easter Sunday to Pentecost Sunday are celebrated as one feast day, the “great Sunday.”
The Sundays of this season are regarded as Sundays of Easter and are so termed; they have precedence over all feasts of the Lord and over all solemnities. Solemnities that fall on one of these Sundays are anticipated on the Saturday. Celebrations in honor of the Blessed Virgin Mary or the saints that fall during the week may not be transferred to one of these Sundays.
Intercession should be made in the Eucharistic Prayer for the newly baptized. It is also appropriate that children receive their first communion on one or other of the Sundays of Easter.
This sacred period of fifty days concludes with Pentecost Sunday, when the gift of the Holy Spirit to the apostles, the beginnings of the Church, and the start of its mission to all tongues and peoples and nations are commemorated.
“It is proper to the paschal festivity that the whole Church rejoices at the forgiveness of sins, which is not only for those who are reborn in Holy Baptism, but also for those who have long been numbered among the adopted children.” By means of a more intensive pastoral care and a deeper spiritual effort, all who celebrate the Easter feasts will, by the Lord’s grace, experience their effect in their daily lives.
Source: The Catholic Liturgical Library