New York State Police say 16-year-old Kyle McPherson of Andover was driving the ATV late Tuesday night in the Allegany County town of Independence when he crashed on a curve and went down an embankment.
Troopers say McPherson and his passenger, Jocelyn Saunders of Genesee Township, Pa., were both ejected from the ATV.
Saunders was pronounced dead at the scene.
McPherson was taken to Strong Memorial Hospital in Rochester, where he's being treated for head, neck and leg injuries.
The cause of the crash is being investigated.
Independence is located on the Pennsylvania border, 75 south of Rochester. Genesee Township is located near the New York border in neighboring Potter County, Pa.