A teenager was attacked during a night out in Wellingborough town centre.
The 18-year-old was assaulted in Market Street, at the junction with Whitehorse Yard, some time between 3.30am and 4.15am on Sunday, May 24.
He was punched, knocked to the ground then kicked while he was on the ground.
He suffered facial injuries and had to be taken to hospital for treatment.
Officers investigating the assault would like to speak to anyone who helped the man after he had been attacked, or who saw the incident.
Witnesses, or anyone who knows anything about this incident, should call Northamptonshire Police on 101.
Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111.