We provide positive documentation of multiple litters in a single year born to an individual Glaucomys sabrinus (Northern Flying Squirrel) residing in southern Ontario, Canada. The first litter, consisting of four young, was observed on May 18, 2003. The second litter, consisting of five young, was observed 15 weeks later on September 2, 2003. The individual female, identified by a unique ear-tag, established natal nests in different nearby nest boxes. Our finding suggests the Northern Flying Squirrel possesses greater population growth potential than previously thought.