Approximately 10,500 locations of 234 individually marked white-tailed deer (Odocoileus cirginianus) in an 826-ha enclosure at Radford Anny Ammunition Plant in Dublin, Virginia, were analyzed to determine when and why deer wander and disperse from their home range. For the first 10 months after birth, over 95 percent ofall locations were within O.8km ofeach deer's center ofactivity, but of those which lived past 15 months ofage, 30 percent ofthe does and 53 percent ofthe bucks are known to have wandered beyond 1.6km, considered the limit of normal activity, sometime during their lives. The tendency for long movements by does was greatest during spring and summer, especially following temporary breakup of family groups at 1 year of age, and when does were preparing to bear their first fawn at 2 years of age. Bucks moved much more frequently than does, and 19 bucks made 2.5 changes in range, mostly between the ages of 12 and 21 months. The disturbance of chasing by dogs and archery hunting caused many deer to make long movements, but so far as is known, all permanent changes in range were made while the deer were undisturbed. Ten of the 25 changes in range were to areas the deer were known to have visited previously. Breeding season activities caused little irregular movement by does, but nine bucks, most of them yearlings, dispersed immediately before, during, or after the rut. Food, because it was generally plentiful everywhere, and water, because it was used very little, did not appear to be important incentives for dispersal.