Yaraldi is one of a group of languages spoken by the people located at the mouth of the Murray River in South Australia. At the time of this study, information on these languages was very scarce,. They were known to be closely related, and to differ from the languages around them, but there were no living speakers of the language.Early grammars provided the main information for the study - principally the grammar published in 1843 by Rev. H.A.E. Meyer. Basic phonetic data was obtained from tape recordings and field notes provided primarily byDr. Louise Hercus, who interviewed the last speakers of the language in the 1960's. Spectrographic analysis of these tapes was carried out to establish detailed phonetic information. Field work undertaken at the conclusion of the study elicited a number of vocabulary items that largely confirm the conclusions of the analysis. Yaraldi has a rich consonantal system, featuring six different places of articulation for stops and nasals, and four for laterals. There are two rhotics, no fricatives or sibilants, and there is no voicing contrast. Most Australian languages have three vowels, but a five-vowel system is postulated for Yaraldi. Phonological processes are postulated to account for the occurrence of initial consonant clusters, a feature unusual in Australian languages. Finally, a lexicon is presented, with entries in both phonemic and phonetic form, to serve as a basis for further work on the language.