Columbian white-tailed deer (Odocoileus virginianus leucurus) were studied to provide information for management of habitat essential to this endangered subspecies. Vegetation was assigned to major community groupings of rush, thistle, grass, horsetail, and forest. Coverage of 85% of the 790-ha study area provided information concerning utilization of the plant communities by these animals that have adopted a diurnal activity pattern. Communities providing both cover and forage were more heavily utilized than were communities providing cover or forage alone. Communities providing forage alone were used most near adjacent cover. Canada thistle (Cirsium arvense) provided cover in summer and allowed deer to utilize previously unused areas. Browse was not used. Green forage was available throughout the year. Restricting visitors to periphery roads allows continuance of the diurnal activity pattern of the deer and aids public enjoyment. Establishment of patches of permanent woody cover where absent would aid in dispersion of the population throughout the refuge.