Londoners have felt safer since police support officers started going out on the beat, a survey has found.
PCSOs can detain but not arrest suspects
Residents and workers interviewed in Camden and Westminster said they provided a "reassuring presence".
The Portsmouth University study results will be announced at an awards ceremony for Police Civilian Support Officers (PCSOs) on Wednesday.
But another survey in Yorkshire and Humberside found people were confused by the roles of extra police services.
PCSOs, introduced two years ago, have limited powers and can detain a suspect for 30 minutes, but not arrest them.
They have been called "extra eyes and ears" for the police by Metropolitan Police Commissioner Sir John Stevens.
But some rank-and-file officers opposed their introduction claiming it was "policing on the cheap".
50% of Westminster people and 70% in Camden said PCSOs reassured them over safety
More than half in Westminster and almost 75% in Camden said they helped reduce their fear of crime
They argued the support officers' salaries, which are less than a police officer's, should be spent on mainstream recruitment.
The Metropolitan Police Deputy Commissioner Sir Ian Blair will announced the results of the survey at the first PCSO Achievement Awards.
Twelve support officers have been nominated for "outstanding contribution to their local communities".
The survey also found they provided an important link between the police and the community.
Sir Ian said: "The extra uniformed presence on our streets was intended to reassure the public and it is heartening to see that they are having exactly that effect."
Researchers interviewed 1,000 people over twelve months.