This is the first comprehensive account of prolonged hearing loss and its impact on a language that was once spoken fluently. The reader is introduced to a significant deaf population — Yoruba speakers who have been profoundly deaf for more than twenty years and who have no access to hearing aids or speech therapy. These speakers exhibit language loss patterns which mirror acquisition stages in the speech of Yoruba children. This similarity argues for a link between language loss and first language acquisition, and shows that prolonged hearing loss results in the reversal of language.