Koalib is a Kordofanian language belonging to the Heibanian branch. It is spoken by at least 100,000 people currently or formerly living in Sudan"s South Kordofan province. This book is devoted to the phonology of Koalib and has successive chapters dealing with its vowels, consonants, tonal system, syllabic structure, and orthographic traditions. This volume is the first part of a detailed, systematic description of this language. It will be followed by others on the morphology, syntax, and lexicon of Koalib. The dialect chosen for this study is Rere, spoken around the town of Abri in the heart of the Koalib linguistic area. This Phonology of Koalib Language, the first of ist kind, is essential reading for everyone interested in the history, comparative studies, and classification of African languages. This English edition is a translation of the original French version entitled Phonologie de la langue koalibe which was published by L"Harmattan in Paris in 2006. Nicolas Quint was born at Poitiers (France) in 1970. He has a doctorate in linguistics from Université Paris III - La Sorbonne Nouvelle and is also a qualified agronomist. Since 2000, he has been working on the description of Koalib and currently holds the post of Researcher on African Languages at the C.N.R.S. (LLACAN). Siddig Ali Karmal Kokko was born in 1962 in the Abri region of Southern Kordofan (Sudan) and is a schoolteacher in Omdurman. His mother tongue is Koalib (Rere dialect) and, as the principal informant, he has made a vital contribution to the successful completion of this study.