The police-led scheme, called Operation Goodnight, is relying on the support of parents to ensure their children do not stay out late.
Around 600 homes in part of Redruth, west Cornwall, have received letters about the curfew - which is part of an ongoing campaign to reduce anti-social behaviour.
The letters asked parents in the Close Hill area of Redruth to ensure that their 16 year olds were off the streets by 9pm and under 10s were at home by 8pm.
The voluntary scheme is the brainchild of Redruth's neighbourhood policing team with the support of other agencies and residents.
The chairman of the local Helping Hands Residents' Association, Ann Mitchell, said before the launch: "The scheme has started to work already. There are less problems with children late at night."
Another organiser, Redruth town councillor Clive Bray, said ahead of the launch he thought more parents were already taking more responsibility for their children than before.
Neighbourhood beat manager Pc Marc Griffin said the the thrust of the police-led, multi-agency scheme was "putting the responsibility back into the family home."
Beginning tonight, multi-agency patrols will be out on the streets, talking to parents and carers of any young people found out after the curfew times.
"If it is felt that the child is at risk or remains vulnerable then referrals to other appropriate agencies will be made as necessary," said Pc Griffin.
