In the Catholic Church, holy days of obligation or precepts are days on which Catholic Christians are expected to attend Mass, and engage in rest from work and recreation (i.e., they are to refrain from engaging in work or activities that hinder the worship owed to God), according to the third commandment.

The expectation is attached to the holy day, even if transferred to another date, as sometimes happens in the Roman Rite. However, in some countries a dispensation is granted in such circumstances.

The holy days of obligation for Latin Church Catholics are indicated in canon 1246 of the 1983 Code of Canon Law:

Can. 1246. §1. Sunday, on which—by apostolic tradition—the paschal mystery is celebrated, must be observed in the universal Church as the primordial holy day of obligation. The following days must also be observed: the Nativity of our Lord Jesus Christ, the Epiphany, the Ascension, the Body and Blood of Christ, Holy Mary the Mother of God, her Immaculate Conception, her Assumption, Saint Joseph, Saint Peter and Saint Paul the Apostles, and All Saints. §2. With the prior approval of the Apostolic See, however, the conference of bishops can suppress some of the holy days of obligation or transfer them to a Sunday.

Placed in the order of the liturgical calendar, the ten days (apart from Sundays) that this canon mentions are:

There used to be many more holy days of obligation. With the motu proprio of 2 July 1911, Supremi disciplinae, Pope Pius X reduced the number of such non-Sunday holy days from 36 to 8: the above 10 dates (1 January was then the Feast of the Circumcision of Christ) minus the feasts the Body and Blood of Christ, and Saint Joseph. The present list was established in canon 1247 of the 1917 Code of Canon Law, now canon 1246 of the current Code of Canon Law.

Even before the time of Pius X, the bishops in many countries had obtained the Holy See's approval to diminish the number of non-Sunday holy days of obligation, making the total fewer than 36. Today too, episcopal conferences have availed themselves of the authority granted to them to reduce such days to the ten mentioned above.

Non-Sunday holy days of obligation all have the rank of solemnity. Accordingly, if in Ordinary Time one of them falls on a Sunday, the Sunday celebration gives way to it; but the Sundays of Advent, Lent and Eastertide take precedence over all other solemnities, which are then transferred to another day, along with the precept to attend Mass. Occasionally, the Feast of the Sacred Heart may fall on Ss. Peter and Paul's feast day, in which case it takes precedence over the Solemnity of Ss. Peter and Paul; the precept then applies to the feast of the Sacred Heart.^{[citation needed]}