The class Mammalia (mammals) is divided into two subclasses based on reproductive techniques: egg-laying mammals (yinotherians or monotremes - see also Australosphenida), and mammals which give live birth (therians). The latter subclass is divided into two infraclasses: pouched mammals (metatherians or marsupials), and placental mammals (eutherians, for which see List of placental mammals). Classification updated from Wilson and Reeder's "Mammal Species of the World: A Taxonomic and Geographic Reference" using the "Planet Mammifères" website.

Subclass Yinotheria (the monotremes)

Order Monotremata (monotremes, egg-laying mammals)

Subclass Theria

Infraclass Metatheria (marsupials)

Superorder Ameridelphia

Order Didelphimorphia (American opossums)

Order Paucituberculata

Superorder Australidelphia

Order Microbiotheria (monito del monte)

Order Notoryctemorphia (marsupial moles)

Order Dasyuromorphia (marsupial carnivores)

Order Peramelemorphia (bandicoots and bilbies)

Order Diprotodontia (diprotodont marsupials)

Suborder Vombatiformes (wombats and koalas)

Suborder Phalangeriformes (possums and gliders)

Suborder Macropodiformes (kangaroos, wallaroos, wallabies)