All young people have been banned from entering a town centre at night unless they are accompanied by an adult in a bid to reduce bad behaviour.
Under-16s will be excluded from the centre of Barnsley between 9pm and 6am if they are not with an adult, South Yorkshire Police said.
South Yorkshire Police and Barnsley Metropolitan Borough Council jointly applied for the order, which began yesterday and will run for six months.
Police will also be able to use the powers to disperse groups of two or more people from anti-social behaviour blackspots and target rowdy night-time revellers or football fans.
Inspector Julie Mitchell said: "Many interventions have been put in place by the police and partners and, although some measures have had some success, nuisance behaviour still persists on an almost daily basis.
"The common theme that appears to cause the most concern is rowdy, inconsiderate and abusive behaviour. This behaviour is often from people in large groups and has led to members of the public and business community reporting the feeling of being harassed and intimidated.
"The order is not intended to be applied without discretion; we want to encourage residents and visitors to come into the town centre for retail and leisure."
The force has previously used under-16 curfews in residential areas of Barnsley in a bid to stop groups of youths "loitering".
However, civil liberties campaigners said the current town centre ban will ruin community spirit and simply push problems elsewhere.
In a similar curfew last year, unaccompanied under-16s were banned from the town centre in Bangor, Gwynedd, between 9pm and 6am, prompting campaigners to brand it a "draconian" move more suited to North Korea than North Wales.
The Children's Commissioner for Wales, Keith Towler, also strongly criticised the order and warned that it would "criminalise" all children and young people.
Mr Towler said: "This is a heavy-handed and ineffective way of combating anti-social behaviour."
Civil liberties campaigners have branded the current curfew in Barnsley town centre "totally wrong" and said it will severely undermine respect for the law.
Nick Pickles, director of Big Brother Watch, said: "Dispersal orders are a blunt, crude tool that at best moves the problem to somewhere nearby.
"It is a sign that the police have lost control of the streets and yet does nothing to restore either the community spirit or respect for the law that has been lost.
"It's simple - if people break the law, harass people and cause distress then the police should arrest them.
"The idea that simply by being under 16 and in town is grounds for the police to take you home seems a waste of time and resources.
"To treat every group of young people as criminals is totally wrong and a blatant infringement on people's rights to move around Barnsley."