They contain a vast diversity of small to mid-sized songbirds widespread in the Austropacific region.

This group was proposed based on the phenetic DNA-DNA hybridization studies of Charles Sibley et al.. A more modern definition of a monophyletic Meliphagoidea based on cladistic analysis was made by ornithologists at the American Museum of Natural History.

However, later work indicated that the Pardalotidae are more closely related to the Meliphagidae (honeyeaters) and could be considered a subfamily within them.

But some ornithologists maintain that separating the spinebills and pardalotes into separate families would mean creating two monotypic families with a mere six species in total, and so keeping the spinebills within the Meliphagidae and possibly merging the pardalotes therein as well seems to be a more sensible course of action.

This is now no longer favoured; as more recent work show that they form a distinct lineage of uncertain relationships; all that can be said at present with reasonable certainty is that the Petroicidae are neither Passerida ("advanced" songbirds) nor a very ancient songbird group.