Information was collected on the nesting ecology of the Great Horned Owl, with particular emphasis placed on aspects of its population and distribution, territoriality and predation. The study was conducted for the two years, 1967 and 1968 in the Thorpe and Topliff hills of central western Utah. Nesting densities on the study area were .36 pairs per square mile in 1967 and .40 pairs per square mile in 1968. Nests averaged one mile apart and were distributed in the periphery of the hills, overlooking the desert valleys. Favorite nest sites were cliff niches, but abandoned quarries and junipers were also utilized. Territorial studies of three nesting pairs indicate that these owls maintained hunting areas ranging from 172 acres to 376 acres in coverage. Owls ranged as far as one mile into the adjacent desert valleys, but extended little activity into the mountainous interior. The black-tailed jackrabbit and desert cottontail contribute the bulk of the Horned Owl food, followed by the kangaroo rat. Other mammals, birds and invertebrates are also utilized, but to a lesser extent.