Holy Days of Obligation

"Remember when you leave this earth, you can take with you nothing that you have received only what you have given: a full heart enriched by honest service, love, sacrifice, and courage.
St. Francis of Assissi

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.

Catechism of the Catholic Church #2180

All Sundays are Holy Days of Obligation.
Remember the Sabbath day, to keep it holy. Six days you shall labor, and do all your work; but the seventh day is a Sabbath to the Lord your God; in it you shall not do any work.

• January 1 (Solemnity of Mary, Mother of God
• August 15 (Feast of the Assumption)
• November 1 (Solemnity of All Saints)

The faithful, however, are encouraged to attend Mass on those days.