Two teenage boys aged 14 and 16 were attacked by a group of people while walking home in Southwater on Sunday April 5.
Police said the pair were walking home near Lintot Square between 11.30pm and 11.45pm when they began arguing with six people.
They were assaulted in Worthing Road, police said.
The 14-year-old was treated by paramedics at the scene for bruising and head pain.
PC Nicholas Wood said: “We would like to hear from anyone who may have witnessed this incident who may be able to help us with our investigation.”
Police are appealing for witnesses. Anyone with information can email firstname.lastname@example.org or call 101 quoting serial 1488 of 05/04.
Alternatively, you can call the independent charity Crimestoppers anonymously on 0800 555 111.