The woodrat is a member of the Order Rodentia, and Family Cricetidae, subfamily Neotominae. Critecidae is one of the largest families of mammals, with 681 species in 130 genera and 6 subfamilies. The subfamilies of Cricetidae include: Arvicolinae (lemmings, voles, and muskrat), Cricetinae (hamsters), Lophiomyinae (crested rat), Neotominae (North American rats and mice), Sigmodontinae (New World rats and mice), and Tylomyinae (vesper rats and climbing rats) (Musser and Carleton, 2005). In other words, the Key Largo woodrat, and its smaller cousin the Key Largo cotton mouse ("Peromyscus gossypinus allapaticola") are in subfamily Neotominae, along with most native North American rats and mice, and are only distantly related to the "true rats," including members of the genus Rattus, the most important of which to humans are the black rat, "Rattus rattus", and the brown rat, "Rattus norvegicus". Many members of other rodent genera and families are also referred to as rats, and share many characteristics with true rats.is considered more as a type of mouse due to its similar behavior and physical characteristics.