From May 13, through August 21, 1986, and again from April 3, through May 18, 1987, a dust devil census was conducted as the Permanent High Explosive Test Size on White Sands Missile Range, New Mexico. In a 260-km2 observation area, a total of 3134 dust devils were counted on 97 days (out of 112 observing days). Within the observation area, the dust devils were concentated in a realtively small area and showed strong correlation with roadways and other cleared areas. However, from the summer of 1986 to the spring of 1987, the center of activity shifted from a relatively undisturbed region to an area whose surface had been recently modified. This shift is attributed to changes in soil moisture and surface thermal properties. It is suggested that the co-location of the center of activity in 1987 with the modified surface is an example of inadvertent weather modification on a very local scale. The dust devils had a daily distribution very similar to that found by Sinclair (1969) in comparable terrain in the vicinity of Tucson, Arizona. The time of the first observed dust devil was very regular on days with dry surface conditions at sunrise and clear skies through the morning. The time of the first dust devil was delayed and the degree of activity reduced if precipitation had occurred on a previous day in the observation area. The production of dust devils often ended abruptly with the onset of an afternoon thundershower in the observations area. ¿ American Geophysical Union 1990