They are a dialect cluster of half a dozen closely related languages.

[1] They are grammatically divergent from the Trans–New Guinea languages, and typically have singular, dual, trial, and plural pronouns.

[2] The Trans–New Guinea identity of Kiwaiian is supported by a relatively large number of basic lexical items.

Ross (2005) tentatively linked Kiwaiian to the erstwhile language isolate Porome.

Kiwaian languages and respective demographic information listed by Evans (2018) are provided below.