The Princess of Wales has said "not enough is being done" for children in their first five years of life.
Writing in The Daily Telegraph, the princess vowed to do "everything I can" to "secure much greater focus on those first crucial few years" of a child's life in the UK.
She said: "Early childhood, from pregnancy to the age of five, fundamentally impacts our whole lives, establishing the core foundations which allow us to go on to thrive as individuals, with one another, as a community and as a society.
"It is the way we develop through our experiences, relationships and interactions at that very young age that shapes everything from our ability to form relationships and succeed at work, to our mental and physical health as adults."
Kate said evidence around the importance of good early years experiences has grown over the past 30 years.
Children's brains also develop fastest in those first five years, she added.
The princess has spoken to scientists, researchers and practitioners to help build a better understanding of the issue.
Last year she established The Royal Foundation Centre for Early Childhood and visited Denmark to learn more about its investment in early years development.
The royal - who is mother to Princes George and Louis and Princess Charlotte - said that there are "fantastic examples of what can be achieved when we recognise the unique potential of early childhood and build a safe and loving world around a child".
In her article, she argued that "not enough is being done".
Kate said: "If we are going to tackle the sorts of complex challenges we face today like homelessness, violence and addiction, which are so often underpinned by poverty and poor mental health, we have to fully appreciate those most preventative years and do everything we can to nurture our children and those who care for them."
The princess's previous charity work has focused on issues such as mental health and homelessness.
Earlier this month she visited refugee families at the Ukrainian Community Centre in Reading.
In a series of at times tearful conversations with mothers who fled their war-torn country, she said she "wished she could do more".