This dissertation is a comprehensive description of Tafi, one of the fourteen Ghana-Togo Mountain (GTM) languages, spoken by approximately 4,400 people in the southeastern Ghana. The description consists of thirteen chapters and is based on a corpus gathered during two fieldwork periods totalling fifteen months in the Tafi area.. The language has a nine-vowel system with root controlled Advanced Tongue Root (ATR) harmony and a complex tonology. The noun class and agreement systems display change in progress. This study also accounts for several distinctive features of the language–a small class of underived adjectives; two adpositional classes and their grammaticalization histories, and a rare split possessor system where singular possessors of kin are marked differently from other possessors; utterance particles; conversational routines; interjections, and ideophones. The form, function and meaning of serial verb constructions, split predicate constructions for some modal-aspectual meanings and a medio-passive construction for predicating properties of undergoers and topic and focus constructions are also covered. The influence of Ewe, the dominant lingua franca, on the structures in Tafi and the distinctions between Tafi and its closest neighbour Nyagbo are highlighted. A selection of glossed and translated texts– folktales, proverbs, riddles and procedural genres–is also included. The thesis is of interest to Africanists, typologists and contact linguists.