This is one of four Marian antiphons, with following versicles and prayers, traditionally said or sung after night prayer, immediately before going to sleep. It is said throughout Eastertide. (That is, from Easter Day through Pentecost, the seventh Sunday after Easter.
The Regina caeli is also said in place of the Angelus during Eastertide.
Queen of Heaven, rejoice, alleluia.
For He whom you did merit to bear, alleluia.
Has risen, as he said, alleluia.
Pray for us to God, alleluia.
Rejoice and be glad, O Virgin Mary, alleluia.
For the Lord has truly risen, alleluia.
Let us pray. O God, who gave joy to the world through the resurrection of Thy Son, our Lord Jesus Christ, grant we beseech Thee, that through the intercession of the Virgin Mary, His Mother, we may obtain the joys of everlasting life. Through the same Christ our Lord. Amen.