Youngsters are missing out on their childhood because we over-protect them, a child play expert claims.
Some parents are afraid of letting children play unsupervised
A reluctance to let children take risks could stop them developing vital skills needed to protect themselves, he adds.
Tim Gill's new book says that instead of creating a "nanny state" we should build a society where communities look out for each other and youngsters.
The book explores several key areas, including children's play, anti-social behaviour and fear of strangers.
In No Fear: Growing Up in a Risk Averse Society, Mr Gill argues that childhood is being undermined by the growth of risk aversion and its intrusion into every aspect of children's lives.
Activities that previous generations of children enjoyed without a second thought - like walking to school on their own - have been re-labelled as troubling or dangerous and the adults who permit them branded as irresponsible, he argues.
Some parents are afraid of letting their children play unsupervised.
But through encountering risks, children learn how to overcome challenging situations, nurturing their character and fostering a sense of adventure, entrepreneurialism, resilience and self-reliance, claims Mr Gill.
Restricting children's play limits their freedom of movement, corrodes their relationships with adults and constrains their exploration of physical, social and virtual worlds, he asserts.
He said: "Although there is a widely-held view that children grow up faster today, in fact their lives are far more controlled than they were 30 years ago.
"In this shrinking domain of childhood, our tendency always to view children as fragile means we are not encouraging them to develop their natural resilience - learning to manage risk in an age-appropriate way.
"This is not an unconditional plea for the deregulation of childhood: children want adults to help them stay safe, and of course we must accept that responsibility.
"But rather than having a nanny state, where risk aversion dominates the landscape, we should be aspiring to a child-friendly society, where communities look out for each other and for children."
The Children's Society takes a similar view.
Penny Nicholls, strategy director at the Children's Society, said: "Over-protecting children carries different risks to under-protecting them, but can still cause long-term damage to their well-being.
"If we continue to try and create a risk-free life for our children, it will be childhood itself that's at risk."
A recent study suggested 43% of adults felt children should not be allowed to play out unsupervised until they were aged 14 or over, she said.
This was "despite the fact that most respondents had been allowed out without an adult at the much younger age of 10 or under."
Mr Gill says making communities more child-friendly would involve providing easy access to welcoming, accessible parks, squares and public spaces; prioritising walking, cycling and public transport over the car; and using city-wide planning to create safer neighbourhoods for children.
His book, which looks at childhood between the ages of five and 11, is published by the Calouste Gulbenkian Foundation.
Mr Gill is an adviser to the ongoing Conservative Party Childhood Review.
From 1997-2004 he was director of the Children's Play Council, and in 2002 he was seconded to Whitehall to lead the first government-sponsored review of children's play.