The small Indian mongoose (Urva auropunctata) is an opportunistic omnivore introduced to sugar producing islands primarily to control rat (Rattus spp.) populations, yet is now considered an invasive pest species on multiple Caribbean islands. Data on home range estimates of mongooses in Puerto Rico and other regions are limited. We fitted 24 mongooses (15 males and nine females) with very high frequency (VHF) radio collars at the Cabo Rojo National Wildlife Refuge in southwestern Puerto Rico and tracked them via radio telemetry for up to six months. The raw mean (SE) minimum convex polygon home range among 24 mongooses was 45.03 (8.30) hectares. The mean (SE) fixed kernel 95% estimate was 38.37 (5.78) hectares, and the 50% core area estimate was 7.89 (1.29) hectares. Our home range estimates are similar to previous estimates in the Caribbean and other islands, but larger than those reported from their native range in India. Our study adds new information to the small body of literature available on mongoose home ranges and is one of the few studies conducted in a lowland dry semi-deciduous forest in southwestern Puerto Rico. Additional research on mongoose home ranges in suburban/rural habitats, as well as in agricultural areas, would provide valuable information for the management of wildlife disease and damage conflicts associated with mongooses in the Caribbean region.