The zebra-tailed lizard (Callisaurus draconoides) is a diurnal territorial insectivore from arid areas of North America. The underside of its tail has a series of black bands on a white background; individuals raise the tail to expose the underside as a social signal and to deter pursuit by predators. We characterized variation in banding of the tail within a population of C. draconoides from Sonora, Mexico, and examined the relationship between characteristics and use of the tail. Number of bands on intact tails was 4–10; individuals who have experienced some natural reduction in their tail can lack bands all together. The proportion of the underside of the tail that was black was 0–0.46. For males, snout–vent length and mass were positively correlated with number of bands and mean length of bars on the tail; snout–vent length, mass, and width of head were positively correlated with the proportion of black on tails. Females in better condition (based on residuals from regression of snout–vent length to mass) tended to have more bars on the tail and a wider head; snout–vent length, mass, and width of head were positively correlated with mean length of band. We simulated predator-prey interactions using humans as predators. Males used tail displays more than females. Individuals encountered in the open were more likely to use tail displays. Neither size of body nor natural reduction in tail was related to use of tail displays. During focal observations for females with reduced tails, rates of tail displays were positively correlated with length of tail. Males with intact tails moved more frequently and fed more often than males with reduced tails.