Kate Middleton (and her new bangs!) returned to work on Thursday, Sept. 17 Credit: Mark Cuthbert/UK Press via Getty Images

Back in style! Kate Middleton returned to public duty on Thursday, Sept. 17, visiting a children's mental health center in London — and she looked stunning!

The 33-year-old royal showed off her beautiful new hairdo, complete with cheek-length bangs, and opted for a black and white houndstooth Ralph Lauren silk “Austin” dress ($1,595) for the occasion, which marked her return to work after spending a quite summer with Prince George, 2, and Princess Charlotte, 4 months, at their home in Anmer Hall, Norfolk. She teamed the outfit with Stuart Weitzman “Power” pumps and a Mulberry suede clutch.

The Duchess of Cambridge was happy and relaxed, looking tanned and toned after a low-key summer break out of the public eye. Her visit to the Anna Freud Centre will enable her to learn more about how the organization is helping to change mental health care for children and young people.

Prince William's wife greeted staff at the center when she arrived at 11:30 a.m. local time, and then went inside for a tour. She will later visit the site of its planned Community Campus in another part of London, before also calling into The Family School, a charity sponsored by the Anna Freud Centre, which has more than 60 years of experience of working with children suffering from serious emotional and behavioral issues.

A source tells Us Weekly that the Duchess is feeling "refreshed and full of energy," following her low-key, family-focused break.

"This summer has been their quietest so far in terms of being able to just focus on family life and keep themselves tucked away out of sight," the source said. "It was so nice to be able to go to Anmer after the birth of Charlotte and not be seen for a while."

?A Kensington Palace spokesperson tells Us that her choice of first post-birth visit “reflects her interest in child mental health issues and the importance of early intervention and working with the whole family to provide children with in-school mental health services.”

Can't get enough of Us? Sign up now for the Us Weekly newsletter packed with the latest celeb news, hot pics, and more!