The 34-year-old royal attended an awards ceremony for the non-profit childrenโs mental health program Place2Be, in London, on Tuesday evening.
Catherine, who has been a patron for the organisation since 2013, helped celebrate kids who have been inspiring examples of positive mental health in their schools.
While the night was about the children, it was one mother that moved Catherine to break royal protocol and embrace her.
Kate gave Ceri Knapton a cuddle after her son, Ethan, 13, told the royal how he used his struggle with Autism and Asperger Syndrome as a way to raise awareness of the condition, ultimately helping others.
Ethanโs proud mum gushed, โI vowed that I wouldnโt cry but was just overcome listening to Ethan. The Duchess just leaned over and said to me โIโve got to give you a hug as a mum.'โ
Adding, โI couldnโt believe it. It was such a kind gesture.โ

Catherine was touched by both Ethan and Ceriโs bravery.
The 13-year-old bravely told Prince Georgeโs mum about how he was bullied during primary school because of his undiagnosed conditions.
โIt was a very difficult time but my diagnosis helped me to cope with what I was experiencing. I decided that I wanted to speak out about it.There is no point in sitting back. Iโd rather stand up and make a difference.โ
Ceri added, โItโs not been an easy few years but he makes me feel so proud. His Autism and Asperger arenโt labels but an explanation of what makes Ethan the boy he is. The fact that he wants to use that to benefit others less able to speak out is just amazing.โ

The mum-of-two is very passionate about mental well-being.

Catherine, William and Harry have set up their Heads Together campaign to end the stigma surrounding mental health that stops people getting the help that they need.
On behalf of the charity, that works with more than 282 primary and secondary schools across Wales, Scotland and England, Catherine made a speech, praising the eveningโs nominees.
โTonight, we are celebrating the truly remarkable work taking place across Place2Be schools in support of childrenโs mental health,โ she began.
โWithout many of the inspiring people gathered here this evening, countless children would not receive such transformational support in their schools. It is because of so many of you, that in their time of need, children have the help, care and attention that will get them through tough times in their lives.โ
โโI am a firm believer that it is absolutely crucial to confront problems as early as possible, to prevent them from escalating into even greater issues later in life. This is why Place2Beโs work โ prioritizing childrenโs emotional wellbeing from the outset โ is so important.โ
Before concluding, โOur young Champion finalists here tonight are extraordinary. You have not only faced challenges but have had the resilience to overcome them. You have also, in your willingness to have open conversations, become young mental health pioneers.โ

The Duchess of Cambridge wore her beloved Preen โFinellaโ dress in black, with a sparkly belt. She first wore the design in red, during her 2016 Canada tour.
Earlier that day, the mum-of-two attended a childrenโs tea party at the Natural History Museum.
The tea party was held in honour of Dippy the Diplodocus, an enormous plaster-cast skeleton and one of the museumโs most famous exhibits.
Next year theyโll bid Dippy farewell, with the dinosaur set to go on a nationwide tour in January 2017.
And heโll have one royal fan that will miss him terriblyโฆ Little Prince George!

Prince George loves T-Rex because it is โthe noisiest and scariestโ of the Jurassic creatures!
The proud mummy told ten-year-old Elizabeth that her eldest โlikes dinosaurs and volcanoesโ and that T-Rex is his favourite because it is โthe noisiest and scariestโ of the Jurassic creatures, adding that he is currently studying them at school.
The museumโs director Sir Michael Dixon also revealed, โGeorge is very keen on dinosaurs โ apparently he would have loved to come today.โ
โ[Catherine] did remark on the fact that as her children get older she is going to have to mug up on the names of dinosaurs.โ
While thereโs no word on Charlotteโs favourite Jurassic creature, Kate did say that her little munchkin has become โextremely chattyโ and โalways wants to have a play dateโ with her big brother.

Little Charlotte adores spending time with her big brother!