Parents are "running themselves ragged" ferrying children from one activity to another and cocooning them from risk.
Mrs Lang, head of Walthamstow Hall, Sevenoaks, Kent, said some children at her school did not own overcoats because they were brought to school, wearing their blazers, in a car every day.
She told the GSA conference in Bristol yesterday: "Children aren't allowed to walk to school or catch a train or bus. They can't disappear for hours into the countryside or town. They have to be supervised and entertained at all times. Their parents run themselves ragged to fill the hours when once they would just have gone out to play or mucked around.
"So the poor kids have gym club on Monday and tennis on Tuesday and violin lessons on Wednesday and extra maths on Thursday and Brownies on Friday - all worthwhile activities in themselves and in moderation, but it's a frenetic life."
As a result, she said at a press briefing earlier, "They never have to wait at a wet bus stop, never had to buy a ticket, never have the fun of sitting on the top of a double-decker bus in London and of learning to be independent."
We were in danger, she added, of rearing a generation that could not assess risks and which might be tempted into "drink and drugs and dodgy sex and driving too fast" to satisfy their natural urge to be daring.
She said that we had to stop thinking in such extreme terms. "We hear about Dunblane. We hear about murders and rapes because information about them is so universally available. We are maybe exaggerating their likeliness."
Parents and teachers should ensure that young people knew what to do if there were a mishap rather then trying to prevent a possibility of them ever coming into contact with a mishap.
"If we teach children in a blanket way that all strangers are evil, that they should never smile at a strange adult, that they should hurry from door to door, we are breeding an unhealthy climate for them."
Schools, too, were under pressure to cocoon children because they were constantly in fear of the worst-case scenario.
"Schools are deeply afraid of slipping up in some way ... they are afraid that putting a foot wrong with a parent or a hand wrong with a child will result in a damaging court case."
She admitted that when she was at school she had not been a terribly good girl. "I always have a soft spot for those who break the rules provided that they are not doing it out of malice."Reuse content