National Day is the highlight of the Luxembourg Grand Ducal Family's annual calendar. Festivities start on 22nd June with fireworks and the ceremonial Changing of the Guard. Then on the 23rd the whole family gather for an official ceremony and a service of thanksgiving at the Cathedral Notre-Dame. 

For the 2015 ceremony, the whole family was in attendance for the Te Deum to celebrate National Day: all four of Maria Teresa and Henri's children were in attendance alongside their spouses (including Louis's now ex wife Tessy). 

Stephanie brought plenty of sunshine to the event with her outfit. She wore a white hat, white open toed shoes, and a bright yellow dress with a boat neckline. The dress is from French designer Paule Ka, a popular brand amongst royal ladies.