Two brothers: Prince Willem Alexander, Prince of Oranien (b. 27 April 1967) and Prince Johan Friso (b. 1968).
On 16 December 2000, after a five-year relationship, Prince Constantijn announced his engagement to Ms Laurentien Brinkhorst (Princess Laurentien).
May 2001: Wedding in Haag
The couple's civil marriage on 17 Mai 2001 was followed two days later by the church ceremony.
He received his primary education in Baarn. After his mother had acceded to the throne in 1980, the royal family moved from Drakensteyn Castle in Utrecht to Huis ten Bosch Palace in The Hague and Prince Constantijn received his secondary education at the Eerste Vrijzinnig Christelijk Lyceum, where graduatewd with VWO-levels in 1987.
After studying languages in France for a year, he started University at Leiden, majoring in civil law.
After graduation in January 1995, he worked for the cabinet of the Dutch European Commissioner Hans van den Broek, father of Princess Marilène, and specialised in difficulties concerning refugees.
He continued to work there in various capacities until the end of 1999. In December 2000, he was awarded Master of Business Administration at European Institute of Business Administration in Fontainebleau, France.
As part of his training, Prince Constantijn spent last summer working for the International Finance Corporation of the World Bank Group in Washington D.C.
After their marriage, Prince Constanijn and Princess Laurentien reside in London, where he works for strategic consultants Booz, Allan and Hamilton as company advisor.
The Prince is interested in asylum problems, European integration, the internationalisation of education, information society trends and international relations.
It is only rarely that Prince Constantijn attends public events in his capacity as a member of the Royal House.
The younger members of the Royal House have made a conscious decision to pursue their own careers, and lead their lives as they choose.
Prince Constantijn is a keen sportsman. He enjoys football, tennis, golf and skiing. His other hobbies include drawing, cooking and reading
As King Harald he is descendant of Wilhelm, Duke of Nassau (1792 – 1839). His mother Queen Beatrix and King Harald are third cousins once removed (firmennings barn).