Nine-banded armadillos (Dasypus novemcinctus) are the only free-ranging vertebrates other than humans known to exhibit naturally occurring infections of Mycobacterium leprae, the causative agent of leprosy, but little is known about ecological consequences of leprosy in wild populations. We studied a population of armadillos in western Mississippi during the summers of 2007 and 2008. Consistent with previous work, we found no evidence of leprosy in juveniles or yearlings, suggesting no vertical transmission of disease. In 2008, a higher proportion of adult females were leprosy-positive than were adult males. Across both years, leprous females were significantly larger than nonleprous females, but a higher proportion of leprous females were lactating and lactating females were larger than nonlactating females. The behavior of leprosy-positive and leprosy-negative animals did not differ. Leprosy-positive individuals tended to be spatially clumped, but these results were not statistically significant. Our findings suggest leprosy had minimal impacts on individuals in this population of armadillos, which is a surprising and unexpected result given the substantial costs of infection documented in the laboratory.