Community support officers have had no impact on levels of reported crime, Home Office researchers have found.
CSOs wear a blue-trimmed uniform
The civilian patrol, which has no power of arrest, was launched three years ago by the government to tackle low-level crime and anti-social behaviour.
The Home Office study found CSOs had no "measurable impact" on recorded crime.
But the department said they were a "reassuring presence" in the community and tackled crime and bad behaviour that was largely unreported.
The CSOs, introduced by former Home Secretary David Blunkett, wear a uniform with a blue trim to distinguish them from police officers.
They spend the majority of their time in contact with the public, often patrolling the streets on foot.
The report stated: "No discernable differences were found in the trends in the numbers of crimes and incidents between areas with and without CSOs, before and after their introduction."
But the authors added that this was "because many of the incidents dealt with by CSOs were not categorised as crimes".
A Home Office spokeswoman said the evaluation of the country's 6,300 civilian officers was largely positive.
She said they had been well-received by the public and "they are valued by their communities and have made residents feel safer".
The evaluation of CSOs throughout England and Wales was carried out between July 2004 and June 2005.
The government wants to see 24,000 officers in the country by 2007/08.