The Baptism of the Lord is the name of a feast day observed in the Roman Catholic Church. The feast commemorates the baptism of Jesus by St. John the Baptist.

From 1970 to the present, in every country except the United States, the Baptism of the Lord has been celebrated on the first Sunday after the Epiphany, or January 6 (prior to that year the Feast of the Holy Family was observed on this Sunday; since then the latter has been marked on the Sunday between Christmas and New Year's Day, or December 30 in years where both Christmas and New Year's Day fall on Sunday). In the United States, an exception to the above arises in years when either January 7 or January 8 is a Sunday, due to the fact that in the U.S. Epiphany is always observed on a Sunday (specifically, the Sunday after the first Saturday in January). When this occurs, the Baptism of the Lord feast is transferred to the following day, a Monday, but is not made a holy day of obligation.

Regardless of the actual day on which the Baptism of the Lord falls, the next day marks the start of the first installment of Ordinary Time.