Sloth remains recovered from Actun Lak, Cayo District, Belize, during archaeological excavations by the Pacbitun Regional Archaeological Project include numerous though mainly fragmentary elements. Among the identifiable remains are a lower molariform tooth and several elements of the manus and pes. Although no complete cranial and long bone postcranial remains are available, the sloth is confidently assigned to the nothrotheriid species Nothrotheriops shastensis (Sinclair). This is the most southern certain record of the North American genus Nothrotheriops Hoffstetter and the first record of a nothrotheriid from Central America. Based on our knowledge of the species' diet and habitat preference from dry caves In the southwestern United States, its presence in Belize has paleoecological and biogeographic implications. The Belize remains clearly Indicate that sloth diversity in northern Central America was greater than previously suspected. They also suggest that a greater variety of habitats existed In this region during the Pleistocene, and that vegetation communities underwent more dramatic changes during this Interval than previously thought.