The relationship between captive red squirrels (Tamiasciurus hudsonicus) and grey squirrels (Sciurus carolinensis) was studied by comparing the behavior or mixed pairs and conspecific pairs in a large outdoor cage containing one primary nest box above ground and another exposed on the ground surface. While red squirrels always shared the nest box with conspecifics, grey squirrels never did so. When both species were present, the grey squirrels occupied the nest box, but shared it 37% of the time with the red squirrels. No fighting or wounds were observed. The much publicized aggressiveness of the red squirrel toward the grey may be a function of territorial behavior in certain parts of its range (conifer forest) rather than an inherent characteristic of the species.