The ranges of Neotoma lepida and Neotoma fuscipes overlap in the Mohave Desert of southeastern California. Food resources of these woodrats were analyzed to determine degree of overlap and other possible competitive interactions. In most aspects of habitat, the two species are distinctly separated, but analyses of food caches and stomach contents revealed that allopatric N. fuscipes and N. lepida both prefer Quercus turbinella , whereas N. lepida switches to Juniperus califomica when sympatric with N. fuscipes . Behavioral interactions were investigated in laboratory test situations for evidence of a possible mechanism of competitive interaction. The results suggest that N. fuscipes is behaviorally dominant over N. lepida , and so maintains competitive superiority over the latter in exploitation of a preferred food resource.