Constitution Day (Danish: Grundlovsdag [ˈɡ̊ʁɔnlɒwsˌdæːˀ]) is observed in Denmark on 5 June.

Though it has never been an official national holiday, Constitution Day was a half-day off work from 1891 until 1975.

[5] The day is widely celebrated throughout Denmark with church congregations, associations and political organisations meeting for what are essentially "secular services".

[3] These services include the raising of the Dannebrog (the Danish flag), a short speech by a local politician or celebrity, and collective singing (Danish: fællessang).

The constitution was completely rewritten in 1866, 1915 (when women's suffrage was introduced), and most recently in 1953, the latter two rewritings also on 5 June.