The Monegasque royal was busy at the weekend watching her pretty 16-year-old daughter Pauline Ducruet take part in the European Junior Swimming and Diving Championships in Helsinki, Finland.
And while Stephanie had her best smile ready for her daughter, she was clearly a little nervous too – putting a hand to her mouth and watching with intent as Pauline launched herself off the springboard.
The youngster – who is growing into an attractive and poised young woman, not unlike her cousin Charlotte Casiraghi – took up diving four years ago.
She represented Monaco at the World Junior Diving Championships in Aachen, Germany, and perhaps has designs on being an Olympic competitor – as her future aunt Charlene Witstock once was.
It seems being sporty runs in the family. Pauline's mum did gymnastics to a fairly high level in the Seventies, and her uncle Prince Albert has represented Monaco in the Olympic bobsleigh team.
Despite her valiant efforts in the three metres competition, Pauline didn't make it to the final twelve, finishing 22nd in a field of 24. In the one metre section she made it to 19th in the preliminaries.
But if she's half as plucky and determined as her mother, she won't be put off, and will soon be back on the diving board, hoping to improve her scores.
Pauline is one of two children Stephanie had with her former bodyguard Daniel Ducruet. The princess fell in love with the dashing bodybuilder when he accompanied her on a tour to promote her music album in the early Nineties.
The two welcomed Pauline two years after her brother Louis was born - and married in 1995, but divorced a year later.
Stephanie went on to welcome another child, daughter Camille Marie Kelly Grimaldi in July 1998.
She has never made public the name of the girl's father.