They are sometimes included in the Trans–New Guinea proposal; Usher links them with the Engan languages in a Central New Guinea Highlands family.

The languages are:[2] Several of the Chimbu–Wahgi languages have uncommon lateral consonants: see Nii, Wahgi, and Kuman for examples.

Chimbu–Wahgi languages have contrastive tone.

[3] The singular pronouns are: Dual *-l and plural *-n reflect Trans–New Guinea forms.

Middle Wahgi reflexes of proto-Trans-New Guinea (pTNG) etyma:[3]