Koninkrijksdag (Papiamento: Dia di Reino, English: Kingdom Day, West Frisian: Keninkryksdei) is the commemoration of the signing of the Charter for the Kingdom of the Netherlands on 15 December 1954 in Aruba, Curaçao, the Netherlands, and Sint Maarten.
Kingdom Day is, unlike Koningsdag (English: King's Day), not an official national holiday, but government buildings are instructed to fly the flag of the Netherlands.
As of 2010, the charter governs the relationships between the Netherlands, Aruba (since 1986), Curaçao and Sint Maarten (since 2010).
[3] In 2008, Naturalisatiedag (English: Naturalisation Day) in the Kingdom of the Netherlands was moved from 24 August, the day on which the Constitution of the Netherlands was signed, to 15 December, the day on which Queen Juliana signed the Charter for the Kingdom of the Netherlands.
On Naturalisation Day, newly naturalized citizens officially receive their Dutch citizenship.