Duchess of Cambridge resumes royal duties with charity visit
The Duchess of Cambridge has visited a children's mental health charity - her first official solo engagement since the birth of Princess Charlotte.
Catherine visited the Anna Freud Centre, in London, which conducts research into the issue, along with caring for children and young people.
While there, she donned a pair of 3D glasses to take part in a game to aid concentration and co-ordination.
The duchess also met senior managers and chatted with parents and children.
During the visit - her first since giving birth to her daughter in May - Catherine joined 12-year-old Capone in a game to keep track of a tennis ball jumbled up among a group of others.
She also tried her hand at the centre's cardio wall where pupils are encouraged to hit coloured lights in a given time period.
The duchess then met parents and their children on a tour of the school, and discussed the charity's plans for a new centre of excellence.
By Peter Hunt, BBC royal correspondent
All senior royals need causes to champion. It's not enough nowadays to just turn up to major events.
At the start of his long wait to fulfil his destiny, Prince Charles solved the problem of what to do with his time by founding the Prince's Trust.
Younger royals are encouraged to support existing organisations, rather than launch one themselves.
Prince Harry obviously ignored that advice when he set up his charity in Lesotho.
With this visit today, the Duchess of Cambridge is signalling that one of her key focuses will be the care of children and young people who are experiencing mental health problems - problems said to affect one in 10 of that age group.
The hope among those she met today is that Catherine's involvement will help to de-stigmatise a problem and bring light to something which, to a degree, has been in the shadows.
Catherine visited one classroom to watch as parents reviewed their children's behaviour.
Among the children who met the duchess was Mia, 12, who has attention deficit hyperactivity disorder and a condition known as oppositional defiant disorder.
Mia, who has been attending the school for a year, said: "I thought she was going to be very, very posh but she's actually really, really nice. I didn't expect that."
She added: "Coming here has really helped me with my self control and temper and confidence."
Neil Dawson, one of the co-founders of the school, said the royal visit had been "very helpful" to the charity.
"Anything to do with mental health is very much at the bottom of the pile in medical terms," he said.
"To get somebody who puts a lot of emphasis on supporting it, that's absolutely brilliant."
Arriving at the centre, the duchess was greeted by Peter Fonagy, the charity's chief executive, who praised her visit as a milestone for his organisation.
The visit is "a very significant step on our journey to try and establish a good mental health for children and young people in England", he said.
Michael Samuel, chairman of the charity's trustees, told Catherine and other guests it was "no secret to anyone in this room that mental health is fast becoming an overriding priority for us all".
"The attention that mental health is now getting is long overdue but the harsh reality of the situation is this - one in 10 children and young people, and one in four adults experience mental issues at some time in their life," he said.
The centre, which began life in 1941, is named after Anna Freud, a pioneer of child psychoanalysis and daughter of psychoanalyst Sigmund Freud.
It is planning the development of a new centre of excellence in London's King's Cross, which will see experts in mental health, neuroscience and education work with children and families to develop new treatments and approaches.
The family school, which opened on a temporary site in September last year, provides alternative education for children who are at risk of exclusion and are struggling to achieve.