Jackknife diversity estimates (n2= inverse Simpson diversity index) for surface-active Collembola were examined along a watershed in the Chihuahuan desert of southern New Mexico. Chord distance measures indicated low similarity in collembolan species composition among the six sites. However, assemblages at the top (black grama grassland) and bottom (mesquite fringe of playa) of the gradient were similar to each other, possibly reflecting available soil nitrogen. There was no significant correlation between Collembola and either weekly or long-term precipitation patterns. Populations of truly epigeic Collembola appeared unaffected by rainfall but were significantly, though weakly, correlated with long-term temperatures.