The Splendid Fairy-wren, Malurus splendens, is one of 13 species in the genus Malurus, which, in turn, is one of five genera in the endemic Australasian passerine family Maluridae (Schodde 1982). Only a few of the 26 malurids have been studied sufficiently closely to reveal their social organization. In seven species, individuals have been caught and colorbanded so that each could be identified in the field. In each case they have been found to breed cooperatively, and it is likely that this trait may be widespread throughout the family.

The malurids are characterized by having 10 (or fewer) tail feathers, certain distinctive skull features, and a gap in the feathering between the scapulars – otherwise they are typical small passerines. They are not closely related to the wrens of Eurasia and the Americas (the Troglodytidae), despite the unfortunate similarity of their common names.

Adult birds of the genus Malurus are strongly sexually dimorphic, with the males being brilliantly plumaged whilst the females are usually a sedate gray-brown. Such marked sexual dimorphism is unknown in other cooperative breeders. Malurus splendens, or splendens as we shall call them from here on, are a vivid example of this dimorphism which becomes apparent in the first spring after they are hatched. Juveniles and immatures of both sexes are brown like the females, whilst the males are brilliant blue and black.