Sundays during Lent have a penitential character, but one markedly different from that of the weekdays of Lent. Because Sunday is primarily a day of celebration of the Resurrection (Catechism, nos. 2174, 2177), it is not counted among the “forty days” of Lent that are traditionally marked by fasting.
“The Sunday Eucharist is the foundation and confirmation of all Christian practice” (Catechism, no. 2181) and retains its essential character as a day marked by “worship owed to God, the joy proper to the Lord’s Day, the performance of the works of mercy, and the appropriate relaxation of mind and body” (Catechism, no. 2185).
Nevertheless, the entire season of Lent, including the Sundays of Lent, is a time of penance. The penitential character of Sundays of Lent is reflected in the wearing of violet vestments and the prayers and readings of the Sunday Masses. It is also reflected in the prohibitions of the singing of the Gloria and the Alleluia, the adorning of the altar with flowers, and the playing of the organ and other instruments (except for the purpose of accompaniment).
The discipline of the Church and the piety of Christians throughout the centuries demonstrate that penance is expressed differently on Sundays of Lent from weekdays of Lent. In the early Middle Ages in the West, the weekdays of Lent were days of fast (one meal) and abstinence (at that time, from dairy products as well as from meat), while Sundays of Lent were days of abstinence only. The Holy See later permitted meat and dairy products to be eaten on Sundays of Lent. Today, of course, only Ash Wednesday and Good Friday are days of fast and abstinence (from meat), while all the Fridays of Lent are days of abstinence.
Penance extends beyond fasting. The Catechism of the Catholic Church teaches:
“The seasons and days of penance in the course of the liturgical year (Lent, and each Friday in memory of the death of the Lord) are intense moments of the Church’s penitential practice. These times are particularly appropriate for spiritual exercises, penitential liturgies, pilgrimages as signs of penance, voluntary self-denial such as fasting and almsgiving, and fraternal sharing (charitable and missionary works)” (no. 1438).
Sundays of Lent, then, have a penitential character, which may include spiritual practices such as prayer, almsgiving, pilgrimages, and retreats, without in any way losing the sense of their being set apart as the “Lord’s Day.”
Click here for more on the history of Lenten observances.