This is the grammar of a language originally spoken by perhaps 2000 members of the Yidiɲdi, Guŋgaɲdi and Madaɲdi tribes, living in rain forest just to the south of the present city of Cairns, North Queensland. The writer collected some data on Yidiɲ from 1963, and worked intensively on the language from 1971 to 1975. Although there are only a handful of speakers remaining, fluent text material was obtained from Tilly Fuller (who died in 1974), Dick Moses and George Davis. The eagerness of the main informants to have their language recorded, together with their intelligence and perceptiveness, has led to a full range of data being obtained for every level of linguistic description.

Yidiɲ is quite close genetically to its northerly neighbour Dya:bugay, which is known from a short grammatical sketch by Hale (1976a); they are as similar as, say, French and Spanish. Comparison with Dya:bugay and reconstruction of aspects of proto-Yidiɲ–Dya:bugay–as well as more general reference to on-going work on comparison and reconstruction for the whole Australian language family – helps to explain many morphological alternations and irregularities in Yidiɲ.

Yidiɲ is as different from its southerly neighbour, Dyirbal (see Dixon 1972) as it is from almost any other language in Australia (while still showing typological similarities characteristic of Australian languages as a whole). Important points of grammatical difference are commented on, in small print, as are a number of interesting surface similarities (some of which may be the result of areal diffusion).