The precept of the Church specifies the law of the Lord more precisely: "On Sundays and other holy days of obligation the faithful are bound to participate in the Mass." (CIC, can. 1247) "The precept of participating in the Mass is satisfied by assistance at a Mass which is celebrated anywhere in a Catholic rite either on the holy day or on the evening of the preceding day.
On December 13, 1991 the members of the National Conference of Catholic Bishops of the United States of America made the following general decree concerning holy days of obligation for Latin Rite Catholics:
In addition to Sunday, the days to be observed as holy days of obligation in the Latin Rite dioceses of the United States of America, in conformity with canon 1246, are as follows:
Whenever January 1, the solemnity of Mary, Mother of God, or August 15, the solemnity of the Assumption, or November 1, the solemnity of All Saints, falls on a Saturday or on a Monday, the precept to attend Mass is abrogated.
* Please note: in the Diocese of Dallas, the Holy Day of the Solemnity of the Ascension of the Lord is always transferred to the following Sunday, the Seventh Sunday after Easter.
* Please note: in the Diocese of Dallas, the Holy Day of the Solemnity of the Ascension of the Lord has been transferred to the following to the following Sunday, the Seventh Sunday after Easter.