We report on aspects of the ecology and natural history of 2 species of armadillos commonly found in a cerrado remnant in southeastern Brazil—the naked-tailed armadillo (Cabassous unicinctus) and the 6-banded armadillo (Euphractus sexcinctus). Armadillos were captured in pitfall traps or by hand, double-marked, and the habitat (campo sujo, campo cerrado, and gallery forests), season, and time of capture were recorded. We also recorded the sex and age of all armadillos, and reproductive condition of females. Population densities were estimated as 0.27 and 0.14 individuals/ha for C. unicinctus and E. sexcinctus, respectively. E. sexcinctus did not preferentially use any of the habitats included in the study area, whereas C. unicinctus preferentially used habitats with a more complex vegetation structure, such as gallery forests. C. unicinctus was diurnal and E. sexcinctus was mainly nocturnal. Neither species changed its activity pattern with season, but C. unicinctus was more active in months with decreased abundance of arthropods—the main food resource consumed by this species. Both species of armadillos appeared to reproduce year-round. Differences in habitat use and daily activity between C. unicinctus and E. sexcinctus suggest spatial and temporal displacement between these species.