The Fourth Sunday in Lent is known by two nicknames: Laetare Sunday and Mothering Sunday.
The first name, Laetare, comes from the Introit (the opening hymn, if you like) in Latin.
Lætare Jerusalem: et conventum facite omnes qui diligitis eam: gaudete cum lætitia, qui in tristitia fuistis: ut exsultetis, et satiemini ab uberibus consolationis vestræ.
Rejoice with Jerusalem, and be glad for her, all you who love her; rejoice with her in joy, all you who mourn over her; that you may suck and be satisfied with her consoling breasts.
These words are from Isaiah 66:10-11a, and serve as an antiphon to Psalm 122, Laetatus sum (“I was glad”). This joy-filled antiphon, paired with a joy-filled Psalm, start off the 4th Sunday in Lent with a noticeably cheerful mood compared to the rest of the season. This is, roughly, the midpoint of Lent, and thus serves as a sort of breather from the rigors of the season where the congregation can take their noses off the grindstone, so to speak, lift up their heads, and take a good look at the joy of Easter fast approaching.
This is traditionally matched with slightly “lightened up” vestments from violet to rose, and the historic Gospel is the feeding of the 5,000, adding to the theme of God strengthening us with provisions along the long hard road of the great penitential season.
The modern lectionary’s take on this Sunday, however, is not quite as noteworthy, and undercuts (or at least diffuses) the impact of “Laetare Sunday” compared to the historic lectionary. It almost doesn’t make sense to retain the rose vestments for this day anymore, and indeed a great many churches, both Roman and Anglican, have not.
The other nickname for this Sunday is Mothering Sunday. This largely stems from a tradition of masters giving their household servants this day off from their duties so they can go visit their own mothers. I couldn’t say where this particular custom originates, though it’s probably not a coincidence that the traditional Epistle of this day begins in Galatians 4:21, discussing the allegory of Hagar the slave woman and Sarah the free woman.
Other traditions associated with this day also add to the enhanced cheerfulness of the occasion: the organ, normally silenced during Lent in pre-Reformation practice, was permitted to be used on this Sunday. Flowers might be placed on the altar. And weddings, traditionally disallowed during the penitential season of Lent, could be held on this one day of the season.
Given that many of those old Lenten traditions are not in place in many of our churches today, there aren’t many ways that we can “lighten up” the 4th Sunday of the season anymore. Plus, given that our Lenten disciplines and modern lectionary and calendar are also a great less rigorous than the days of old, there is far less cause or need for such a day as this. But sometimes knowing about how things used to work can help us reshape our modern practice, and rediscover some of the discipline and mentality that were nearly lost in the 20th century.