The Solemnity of the Ascension of Jesus Christ, also called Ascension Day, Ascension Thursday, or sometimes Holy Thursday, commemorates the Christian belief of the bodily Ascension of Jesus into heaven. It is one of the ecumenical (i.e., shared by multiple denominations) feasts of Christian churches, ranking with the feasts of the Passion and Pentecost. Following the account of Acts 1:3 that the risen Jesus appeared for 40 days prior to his Ascension, Ascension Day is traditionally celebrated on a Thursday, the fortieth day of Easter; although some Christian denominations have moved the observance to the following Sunday. The day of observance varies by ecclesiastical province in many Christian denominations, as with Methodists and Catholics, for example.

Ascensiontide refers to the ten day period between the Feast of the Ascension and the Feast of Pentecost.