Many young pupils 'can't communicate'
Too many children are starting school in England unable to speak in simple sentences or control their behaviour, a study says.
The Early Intervention Foundation's analysis found a fifth of children lacked the expected personal, social and emotional development by age five.
A quarter of children were unable to communicate at the level expected for their age, it added.
The government said it recognised the importance of early years investment.
And this was why it had raised spending by £1bn a year.
'Last a lifetime'
The report is based, in part, on analysis of pupils' results in the latest Early Years Foundation Stage profiles of children at the end of their Reception year.
These goals covering personal, social and emotional development expect children to be able to manage their feelings and behaviour, show confidence in trying new activities, and to speak in a familiar group, among other things.
Expectations on communication and language include being able to listen attentively, express themselves effectively and follow instructions.
Children who are not school-ready will struggle to make relationships with other children, they will find it difficult to play co-operatively and take turns.
They might not be able to follow the class rules or adjust their behaviour for different situations and may not understand that there are consequences to poor behaviour.
They may not be able express themselves very well and may not have grasped the difference between past, present and future tenses, for example.
'Not sign of failure'
They may struggle to tell stories about their own experiences and may find it difficult to respond to questions.
The report also cited figures indicating large average differences in behaviour and emotional health between the poorest and richest children.
These were apparent as early as age three and persisted until age 11, it said.
The foundation's chief executive, Carey Oppenheim, said: "Too many children arrive for their first day at primary school lacking the broad range of skills they need to reach their full potential.
"This can have damaging consequences which can last a lifetime - especially as children with strong social, emotional and communication skills developed in childhood have a better chance of getting a good job and being healthy, than those who are just bright or clever.
"The gap in the development [of] social and emotional skills between children growing up in poor and rich families begins at the age of three.
"Seeking help as a parent must not be seen as a sign of failure."
The call comes as the government is about to introduce new baseline assessments for Reception children.
'Ready to learn'
The foundation called for any baseline assessment to give the same weight to social, emotional and physical development as literacy and numeracy.
A Department for Education spokesperson said: "We are committed to making sure every single child starts school ready to learn - that is why we have increased spending on childcare and the early years by around £1bn per year.
"Families can now access a record amount of free early years education for two-, three- and four-year-olds. The latest research has also shown the quality of these providers is improving, meaning that more children will get the start they deserve. Getting the basics right early on is essential, so that all children can fulfil their potential.
"We agree that parents deserve a more complete picture of their child's development. That is why we are introducing a joined-up health and education review for two-year-olds and have supported the launch of a parent's guide on learning and development up to the age of five."