The Duke and Duchess of Cambridge have left for their first joint event together after Catherine made her expected return of maternity leave.
The parents, who welcomed their third son Louis on April 23, attended the first World Ministerial Mental Health Summit in London.
Catherine wore an impressive lilac long-sleeved dress by the designer Emilia Wickstead, which she was already wearing, combined with bare heels and a pale lavender bag.
Prince William wore a classic black and white suit.
Unusually, both wore recycled clothes that they had previously worn at the same event during their tour of Germany in July 2017.
The couple seemed excited to be together again when the fans waved flags and applauded.
Catherine returned to her royal duties after her six-month maternity leave last week when she visited Sayers Croft Forest School and Wildlife Garden at Paddington Recreation Ground, which helps the emotional and physical well-being of the children.
At the summit on mental health, jointly organized by the Government of the United Kingdom and the Organization for Economic Cooperation and Development, a series of experts and political figures met in an attempt to improve mental health and address the stigma surrounding it .
Kate and William attended the workshop for Children, Youth and the Next Generation, where two case studies from Slovenia and the United States were heard.
Mental health is a problem close to the heart of the royal family, after Kate, William and Prince.
Harry led the The Heads Together campaign through his official charity organization The Royal Foundation in 2016.
The campaign, which has allowed experienced charities to work together, continues to foster a healthy conversation about mental illness.
As part of the campaign, the first Marathon for Mental Health was held in the United Kingdom last year and the CEO of the charity Mind, Paul Farmer, announced that it would "change the conversation about mental health in Britain" as "Nothing I had witnessed."
In the run-up to the 2017 marathon, Harry revealed that he had sought counseling after two years of "total chaos" during his 20 years as he struggled with the death of his mother, Princess Diana.
Meanwhile, last month, Will opened up to meet his problems after witnessing the suffering that his old job as an air ambulance pilot exposed him.
The honesty of the royal family has been hailed as a game changer that has encouraged people with mental illness to speak.
The Heads Together campaign was selected as the 2017 Virgin Money London Marathon charity.
The trio has continued to address mental illness through several projects, including the Mentally Healthy Schools website that Catherine launched and the Mental Health at Work campaign Will unveiled.
Meghan, the Duchess of Sussex is also a passionate advocate for mental health, and has joined her new husband Harry in various events since becoming a sponsor of The Royal Foundation.