The Princess of Wales is "determined" that everyone knows the "critical importance of our early childhood" as she penned a heartfelt open letter ahead of the launch of a "major new awareness raising campaign".
Kate, 41, wrote: "During our very early childhood, our brains develop at an amazing rate – faster than any other time of our lives. Our experiences, relationships, and surroundings at that young age, shape the rest of our lives."
WATCH: Princess Kate reveals why she's excited about new campaign
After teasing the campaign on social media earlier on Saturday, Kensington Palace released images of the Princess, wearing a green pussy-bow blouse and fitted trousers, chatting and playing with children taken during a visit to an East London school last week.
"It is a time where we lay the foundations and building blocks for life. It is when we learn to understand ourselves, understand others and understand the world in which we live," Kate emphasised in her letter. "But as a society, we currently spend much more of our time and energy on later life. I am absolutely determined that this long-term campaign is going to change that."
Outlining her foundation's future plans, she continued: "It will start by highlighting how we develop during early childhood and why these years matter so much in terms of shaping who we become."
NEWS: Royals who are expecting babies in 2023
Kate hosted a group of experts at Windsor Castle earlier this week
To help launch the campaign, the Princess will be joined by a group of experts spanning science, research, policy-making and front-line practice, as well as a host of famous faces from the worlds of music, sport and television.
Kate signed off her letter by writing: "We all need to know the critical importance of our early childhood. They really are years like no other in our lives.
"I urge everyone reading this, to take the opportunity to learn more about this incredible time of life, to think back to your own childhood and how it shaped you, and most importantly, to ask yourselves what you can do to make the world a more supportive and loving place for our children.
"Because healthy, happy children shape a healthy, happy future."
The Princess is launching a new early years campaign
It comes after the Princess revealed her excitement about her new project during a meeting with a panel of eight academics at Windsor Castle earlier this week.
The doting mum to Prince George, nine, Princess Charlotte, seven and four-year-old Prince Louis, told the group: "I feel a bit nervous about it! But excited too. I was talking to the children this morning - the excitement and nervousness gets mixed up together in the same pot."
LISTEN: King Charles: The Man Behind The Crown
Make sure you never miss a ROYAL story! Sign up to The Royal Explainer newsletter to receive your weekly dose of royal features and other exclusive content straight to your inbox.