Quantitative information is presented on defensive behavior of brooding female Plethodon cinereus. Responses of females to brooding and non-brooding conspecifics and snakes were observed in the laboratory. Aggressive defense was exhibited by 91% of attendants and 5% of intruders in encounters between brooding females. Attendants were equally aggressive in encounters with non-brooding intruders (85% for adults and juveniles) and less with hatchlings (44%) none of which showed aggressive behavior. Responses of attendants to intrusion indicate that they may be defending the nest cavity as well as the eggs and therefore are exhibiting both territorial behavior and parental care.