Guillaume has been heir apparent to the crown of Luxembourg since his father's accession in 2000. If he succeeds to the grand ducal throne, he will reign as Guillaume V. He has been honorary chairman of the Board of Economic Development of Luxembourg since 2001. The Hereditary Grand Duke is patron to the Luxembourg Cycling Sport Federation, Youth Hostels Central, National Association of Road Victims, Chamber Orchestra of Luxembourg, Youth Harmony Orchestra of the European Union, as well as to Young Entrepreneurs Luxembourg and Special Olympics Luxembourg Associations. During the summer of 1997, Guillaume participated as a member of Luxembourg Scout Movement in a humanitarian camp in Nepal. He involved in a reforestation project and other actions for the benefit of the less favored communities. In 2017, the Hereditary Grand Duke joined the board of directors of the World Scout Foundation to support the development of scouting around the world. In 1999, he participated in a charitable mission to Aguascalientes to provide the educational and social assistance to young people in one of the most deprived areas in Mexico. After having chaired for more than 10 years in Kräizbierg Foundation, which works for people with disabilities; the Hereditary Grand Duke accepted the title of honorary president in March 2011. Since 18 January 2016, the Hereditary Grand Duke has also been a member of the board of directors of Europäische Stiftung Kaiserdom zu Speyer Foundation.
Marriage and fatherhood
At the occasion of his 30th birthday, he gave interviews during which stated that he was in a relationship with a "dear miss" that had been going strong for more than a year but insisted that they need some more time to evaluate their possible future. On 26 April 2012, the court announced the engagement of the Hereditary Grand Duke to the Belgian Countess Stéphanie de Lannoy. Guillaume and Stéphanie share a common descent from Charles Marie, Prince & 5th Duke d’Arenberg, which means that Guillaume's father and Stéphanie are 7th cousins; thus Guillaume is Stéphanie's 7th cousin once removed. The civil wedding took place on Friday, 19 October 2012; the religious wedding took place on Saturday, 20 October 2012 at the Notre-Dame Cathedral. Guillaume and Stéphanie have a son, named Prince Charles, born on 10 May 2020 at Grand Duchess Charlotte Maternity Hospital in Luxembourg. He is second in the line of succession to the throne of Luxembourg.
Interests
Guillaume is interested in music and sports; he plays the piano and enjoys football, swimming and volleyball. He speaks Luxembourgish, French, German, Spanish and English. He regularly represents his parents in many foreign activities.
Titles and style
His style and title in full is: His Royal Highness Prince Guillaume Jean Joseph Marie, Hereditary Grand Duke of Luxembourg, Hereditary Prince of Nassau, Prince of Bourbon-Parma.
