Dyfed Powys Police is educating people on how to have an enjoyable and safe Hallowe'en.
Posters have been produced to highlight homes where people are happy to be visited by trick or treaters.
The posters also include safety tips for anyone wanting to dress up and go out and about calling at houses.
As part of Not in My Neighbourhood Week, Neighbourhood Policing Teams in Pembrokeshire have been going into schools talking to young people about how their behaviour can affect others.
They will also be increasing patrols during the evening to prevent young people using Hallowe'en as an excuse to commit anti-social behaviour.
Inspector Gareth Thomas said: "While Hallowe'en can undoubtedly be a great deal of fun, it can also be a particularly distressing time of year for some of the more vulnerable members of our communities - especially the elderly.
"Trick and Treaters are therefore being urged to only knock on doors where the poster is displayed.
"We are also working with shops to restrict the sale of eggs and flour in the run up to Hallowe'en.
"Anti-social behaviour can be very upsetting for people and it will not be tolerated especially under the guise of trick or treat."
The Neighbourhood Policing Teams will be increasing evening patrols throughout the weeks running up to Hallowe'en.
Trick or treating advice
• Always go with an adult
• Only to go to houses where you or your friends know the people and know you are welcome
• Only go to houses displaying the 'Trick or Treaters' welcome poster
• Don't talk to strangers
• Don't enter the house always stay on the doorstep