The Duchess of Cambridge is used to topping the news agenda, but now she is to help set it by spending a day as a guest editor.
Kate will join the editorial staff at Huffington Post UK next monthto help raise awareness of children's mental health.
She has campaigned against the stigma surrounding childhood mental illness, and is a patron of several related charities.
During her time at the publication, she will arrange contributions from a selection of leading figures in the area, Kensington Palace confirmed.
The Duchess will also hope to bring recognition to the work done by parents, teachers, researchers and mental health professionals across the UK.
A Kensington Palace spokesman said: "The Duchess of Cambridge has made the mental health of young children a key focus of her work in recent years.
"She is delighted that The Huffington Post will help put a spotlight on this important issue."
Last year, Kate visited charities helping vulnerable children, and publicly spoke about the cause on several occasions.
In a message recorded for Children's Mental Health Week 2015, she called for greater support for young people struggling to cope with problems such as anxiety or depression.
"The stigma around mental health means that they do not get the help they so badly need - this needs to change," she said.
Huffington Post UK editor-in-chief Stephen Hull said they were "thrilled" at the prospect of welcoming Kate in mid-February.
"We are thrilled that the Duchess of Cambridge is joining the HuffPost UK team for a day as a guest editor," he said.
"Dealing with mental health issues has been a major editorial focus for us and I'm very excited to be working together on such an important project."