Police say that 18-year-old James J. Paine was driving along Parkman Hill Road when he swerved to avoid an oncoming vehicle.
Paine reportedly overcorrected, and struck 87-year-old Bernard Currier, who was mowing his lawn at 170 Parkman Hill Road.
Currier was pronounced dead at the scene.
Paine sustained minor injuries when his car rolled onto its roof.
State police say speed appears to have been a factor in the crash.