(Uploaded by Plazi for the Bat Literature Project) Many of the issues archaeologists are confronted with are similar to those encountered by natural resource biologists including increased urbanization and industrialization. We investigated bat use of archaeological structures at Montezuma Castle (i.e., Montezuma Castle Unit and Montezuma Well Unit), Tonto, and Tuzigoot National Monuments, Arizona to determine the impact of bats on archaeological structures. Archaeological sites were checked for bats or bat sign (i.e., guano or urine stains) and recommendations were made regarding bat use of the archaeological sites at each of the monuments. Guano was found in all the archaeological sites checked at Montezuma Castle National Monument. We found #3 individuals of two species day roosting, and approximately 40 individuals of seven species night roosting in the five-story cliff dwelling at Montezuma Castle Unit. A maternity colony of Townsend's big-eared bats (Corynorhinus townsendii) was roosting in Swallet Cave at Montezuma Well Unit. Bats used the crevices in the rock face above the cliff dwellings for roosting at Tonto National Monument. We found small amounts of guano in the tower room of the pueblo at Tuzigoot National Monument. Bats were not causing damage to the archaeological structures.