Koningsdag or Kings Day (formerly known as Queens Day) is the Day when all the Dutch wear Orange, drink Heineken and trade old clothes on the street.

Koningsdag or Kings Day (formerly known as Queens Day) is the Day when all the Dutch wear Orange, drink Heineken and trade old clothes on the street. It is held the 27th of April and the best place is Amsterdam. Kings Day celebrates the birthday of the King of the Netherlands and is supposed to be a day of national unity and "togetherness". The tradition started on 31 August 1885, on the birthday of Princess Wilhelmina, later Queen Wilhelmina. Since 1949, after the accession of Queen Juliana, Queen's Day is Queen Juliana's birthday on 30 April. When Willem Alexander became king the day moved to the 27th of April.

Kings Day is known for its "freemarket" all over the country, where everybody is allowed to sell things in the streets. Other activities during Kings Day are children's games, individual musical performances, and music concerts. The night before Kings Day is celebrated too in most cities, and this is called Kings Night. The largest celebration of Kings Day is in Amsterdam, Kings Night in The Hague and Kings Dance in Rotterdam. During the celebrations as reference to the colours of the House of Orange-Nassau, people dress in the colour orange, which is sometimes called "orange craze".

During the preceding 'koningsnacht' (Kings Night) many bars and clubs throughout the Netherlands (particularly in Amsterdam, Utrecht and The Hague) hold special events catering to revelers that last all night long. This tradition started in the early nineties when pre-Koninginnedag riots were an increasing problem in The Hague. The idea of convincing the rioters that a celebration is a much better way to spend 'Koninginnenach', proved successful. The event draws tens of thousands of visitors every year.