Nicholas Daniel Kalustian, of Martinez, was arrested following an investigation into allegations of an inappropriate relationship with a student at Acalanes High School, police said.
Acalanes High School officials notified police about a relationship between Kalustian and a student last week. Kalustian was placed on administrative leave and instructed not to return to campus, police said.
Police said the relationship between the student and coach had been going on for one year. Police were also notified that Kalustian was working at another school in the area.
Police secured an arrest warrant for Kalustian and he was arrested without incident.
He was booked into county jail with bail set at $100,000.
The case remains under investigation and anyone with information is asked to call police at (925) 283-3680.