A third of five-year-olds are unable to count to 10 or write simple words such as 'cat' and 'dog', according to a report by the head of Ofsted.
Sir Michael Wilshaw said that a 'significant minority' of youngsters start school 'simply not ready' for lessons because they lack basic skills they need to be able to learn.
His comments follow last year's warnings by teachers that rising numbers of children were arriving at school still wearing nappies while others struggled to speak properly.
Sir Michael's report – Getting It Right First Time – quotes 2012 Department for Education figures showing that 36 per cent of children start formal learning without a 'good level of development'.
Children are expected to be able to count reliably to 10, use language such as 'circle' or 'bigger' to describe shapes and sizes, interact with classmates and take turns to talk and show basic control of objects and tools by the time they start full-time school.
But 34 per cent of five-year-olds do not have a good level of communication, language or literacy.
Among children from poorer areas, the figure rises to more than four in 10.
Fifteen per cent of five-year-old boys in England cannot write their own name or short words like 'cat' or 'dog', compared with eight per cent of girls.
Some eight per cent of boys cannot count up to 10, compared with five per cent of girls.
Sir Michael called for improvements in nurseries and childcare and suggested they use imaginative initiatives to better engate with very young children.
For example, Southwater village hall pre-school in West Sussex encourages children to use money and real china cups.
The Ofsted report says: "In the snack area, children spend a very long time selecting their choices and paying for their order with real money. "As well as deciding when and what to eat, they are also learning about numbers and money in realistic situations."
What do you think? Do we start our children too young, compared to Europe, and then expect too much or should we be worried?
More on Parentdish: Preparing your child for primary school