Holy Days of Obligation are the days other than Sundays when Catholics are obligated to attend Mass.  Below are the Holy Days of Obligation for this year in Scotland:

Thursday 14th May – The Solemnity of the Ascension

Sunday 28th June – The Solemnity of St. Peter and St. Paul, Apostles*

Sunday 16th August – The Solemnity of the Assumption of the Blessed Virgin Mary*

Sunday 1st November – The Solemnity of All Saints

Friday 25th December – The Solemnity of the Nativity of Our Lord Jesus Christ

* If St Peter and St Paul (29th June) or the Assumption (15th August) fall on a Monday or a Saturday, the day of obligation will be celebrated on a Sunday.  If All Saints (1st November) falls on a Saturday then the day obligation will be Sunday and All Souls will be on the Monday.  If All Saints falls on a Monday then that day is a day of obligation.