Nantucket, Massachusetts, could provide unique habitat for bats, but few data are available regarding bat populations on the island. We conducted passive acoustic surveys in 2015 and 2016 to inventory bat species and identify seasonal activity patterns. We detected at least 6 species of bats on Nantucket. Lasiurus cinereus (Hoary Bat) and Lasionycteris noctivagans (Silver-haired Bat) were detected as probable migrants, and Lasiurus borealis (Eastern Red Bat), Eptesicus fuscus (Big Brown Bat), and Myotis species were also present in summer. We detected Perimyotis subflavus (Tricolored Bat) in fall and early winter, suggesting that the species may hibernate on the island. In 2016, we mist-netted and radio-tagged Myotis septentrionalis (Northern Long-eared Bat), and documented individuals reproducing and hibernating on Nantucket. Given the persistence of this rare species on the island, we suggest that land-conservation organizations should consider maintenance of mature forest stands in their suite of planned management activities.