Middleton attended her first solo royal engagement since her son's birth last week, when she visited the Paddington Recreation Ground in Ewhurst, England to spend time with local school children.
Showing her thrifty side once again, the Duchess of Cambridge, 36, recycled a stunning lilac Emilia Wickstead dress as she attended the Global Ministerial Mental Health Summit in London with William on Tuesday, coupling the knee-length frock with nude Gianvito Rossi heels.
Both wore outfits we've seen previously, with Prince William choosing a classic black and white suit and Kate choosing a long-sleeved lilac dress by designer Emilia Wickstead, which she wore during her royal tour of Germany in 2017.
The Duke and Duchess have been longtime supporters of mental health awareness, promoting their organization, Heads Together, to help mental health charities and groups around the country and the world.
Eagle-eyed fans of Kate's style will recognise the frock from her and Prince William's royal tour of Germany and Poland a year ago.
William and Kate have always been involved in mental health initiatives through their Heads Together campaign.
The Duke and Duchess had a chance to speak to young delegates at the summit about the challenges and issues they face.
The couple, along with Prince Harry, have been credited with helping break down the stigma surrounding mental health by encouraging open conversations about it.
During the event, William aimed a good-natured ribbing at his wife after Middleton, who studied art history at the University of St. Andrews in Scotland, added a brushstroke to artist Dairo Vargas' painting.
Their last stop was to a Friendship Bench, part of a innovation program from Zimbabwe which aims to teach elderly Zimbabwean women the skills they need to act as city lay health workers.
The duchess first showed off the Emilia Wickstead dress on a trip to Germany past year.
The couple is also preparing for another big event on Friday when William's cousin, Princess Eugenie, celebrates her Royal Wedding to fiance, Jack Brooksbank, at Windsor Castle.