Last Tuesday night, a fight broke out between two groups at Northside Park on Harry L. Drive.
Police say 20 year old Nicholas Reigles picked up a bat, and hit a 16-year-old.
The boy was seriously injured .Police aren't releasing the victim's name.
Reigles is charged with assault.
He was arraigned in the Village of Johnson City Court and sent to the Broome County Jail without bail.