Catholics, once they have reached the age of reason, are
bound under serious sin to be present at the whole of
Mass every Sunday and on every Holy Day of Obligation.
Deliberately to miss Mass on a Sunday or a Holy Day of Obligation
is a serious sin which is forgiven in the Sacrament of Reconciliation.
The obligation to be present at the whole of Mass on Sunday
and Holy Days of Obligation ceases where there is personal
illness, when one has to care for a sick or frail person,
and when one is impeded, e.g., by travelling.
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: