We studied the ecology of a population of the spiny lizard, Sceloporus jarrovii, located in the central Chihuahuan Desert. We compared the ecology of this population to that of other populations of S. jarrovii. Males were larger in snout–vent length, width of head, length of head, and length of femur than females. Mean size of clutch was 5.7. Overall sex ratio did not different from 1:1. However, the sex ratio was 1:2 in spring and summer, and 2:1 in autumn (reproductive period). All lizards were associated with crevices. Size of crevice (thickness) did not increase with snout–vent length of lizards. Mean body temperature was 31.6°C. Body temperature was related to air and substrate temperature. Of the four characteristics of crevices measured, only thickness of crevice was related to body temperature.