The effects of soil moisture and temperature on arthropod communities were experimentally examined in the northern Chihuahuan Desert of New Mexico. Shaded plots were established which lowered the soil temperature several degrees; some plots received artificial rainfall to increase soil moisture. Shading reduced soil temperature at 5-cm depth 7-10 C. Soil moisture at 5 cm accounted for most of the variation in surface activity of subterranean termites (r values between 0.3 and 0.7). Termites did not respond to temperature differences. When all soils were at field capacity, there was no difference in termite activity in shaded and unshaded plots. There were higher densities of microarthropods in litter bags on the shaded plots than on the unshaded plots. Numbers of microarthropods were an order of magnitude larger in litter bags on watered and shaded plots than on other plots. Lower litter temperatures apparently affect litter arthropods more than increased soil moisture. Shade had no effect on ant colonies but there were fewer colonies on the watered plots. There was between 40 and 59% mass loss from creosotebush leaf litter after 7 months on all plots. Water and soil temperature had no effect on decomposition rates.