Submitted in fulfillment of a 2015 Nantucket Biodiversity Initiative grant. I conducted a preliminary acoustic study of bats on Nantucket, in order to inventory species present on the island, and to document the persistence of any northern long-eared bats. Bats were surveyed using passive acoustic monitoring at five sites on the eastern part of Nantucket. Silver-haired and hoary bats were recorded beginning in late July and late August respectively, and continuing into October and early November, suggesting use during the fall migration season. Eastern red bats were recorded from May through early November, and appear to be summer residents. The northern long-eared bat, a federally threatened species, was also documented, using both acoustic and physical evidence. Presence of other Myotis spp. was suggested by auto-classification software, but could not be confirmed via manual identification. Big brown bats and tricolored bats were also present on at least one site on Nantucket.