We studied the influence of prey size and abundance on social organization and space use by eastern coyotes (Canis latrans) in 2 areas of Nova Scotia, Canada. Breeding pairs formed the nucleus of coyote social groups, and these often traveled with 1–3 other coyotes during winter. Increased use of white-tailed deer (Odocoileus virginianus) was insufficient to explain group size and cohesiveness by eastern coyotes. Winter-traveling group size was similar for family groups using deer (X̄ = 2.6) or snowshoe hares (X̄ = 2.7) as a primary prey in winter. Estimated densities of coyotes in winter was 4.3–13.9 coyotes/100 km². Coyotes used the same general areas during winter and summer and from year to year. However, territory sizes decreased with increasing densities of deer (partial r² = 0.21, P = 0.043) and hares (partial r² = 0.40, P = 0.007). During winter, coyotes used areas of high deer density in proportion to their availability, but in some instances, they used areas that contained few or no deer proportionately more than expected, probably because deep snow and few trails increased vulnerability of deer in these areas. Territoriality seemed to prevent coyotes from concentrating in deer wintering areas and kept the coyote : deer ratio relatively low (<1:25).