Owen Sound police have charged an 18-year-old man with multiple counts of sexual assault and sexual interference.
Police say they launched an investigation after teenaged girls began reporting being inappropriately groped at an Owen Sound high school.
The accused is not a student.
The Owen Sound man has been held in custody and has a court appearance later on Thursday.
The man faces eight counts of sexual assault and five counts of sexual interference.
Police say there are no other suspects, and the school has been notified.