We determined characteristics of nest trees and surrounding habitats used by northern flying squirrels (Glaucomys sabrinus) in subboreal forests of northwestern British Columbia during winters 1996–1997 and 1997–1998. Nineteen radiocollared flying squirrels (12 males, 7 females) were located in 82 daytime nests. Animals used an average of 5.6 nest trees (±0.5 SE; range, 3–10) per animal. Core nest areas used by flying squirrels averaged 2.74 ± 0.62 ha in size; areas were more variable for males (range, 0.86–8.58 ha) than females (range, 0.03–2.23 ha). Nest trees were highly variable, suggesting that animals select more for suitable nest sites than for tree size: diameter at breast height was 16.7–79.0 cm, age was 42–174 years, and height was 11.2–32.7 m. A significant proportion of nest trees, however, were larger, older, and taller than trees that were randomly available in the locale of nest trees. Variation in habitats used by flying squirrels in the subboreal spruce (Picea) zone of British Columbia is evidence of the ability of this animal to occupy a wide range of conditions in a region that is not typified by old-growth forests.