Principal Holy Days are a type of observance in the Anglican Communion, including the Church of England. All Principal Feasts are also Principal Holy Days. All Principal Holy Days share equal status; however those which are not Principal Feasts, being fast days within the season of Lent, lack a festal character. They are considered to be the most significant type of observance, the others being Festivals, Lesser Festivals, and Commemorations. Observance of Principal Holy Days is considered obligatory.

The Church of Ireland recognises ten principal feast days and holy days.