There is a paucity of empirical data on gliding abilities of most gliding mammals, including flying squirrels in the genus Glaucomys. I assessed gliding performance of the northern flying squirrel (Glaucomys sabrinus) by calculating glide parameters for 100 glides observed between July 1999 and July 2000 in southern New Brunswick, Canada. G. sabrinus had a glide angle of 26.8° and a glide ratio of 1.98. The difference between the vertical drop at the start of a glide and the vertical rise at the end of a glide was about 1.91 m. Males tended to glide farther than females (X̄ = 19.0 m versus 14.2 m), although sexes did not differ in heights of launch (X̄ = 9.8 m) or landing (X̄ = 2.0 m). Red spruce (Picea rubens) trees were favored as landing sites over hardwood species. Most glides (59%) were with the slope of terrain, allowing a greater net height loss (X̄ = 10.2 m) than initial height of launch. Horizontal glide distance ranged from 3.2 to 45 m, with most glides being 5–25 m.