Dr. Ngonyani's primary research and teaching interests are in language description, the morphosyntax of Bantu languages—particularly how morphological structure is related to phrasal structure—and comparative-historical studies of Southern Tanzanian languages. He has presented at conferences and published on various aspects morphosyntax in Studies in African Linguistics, Lingua,and the Linguistic Review. He has also presented and published articles on language in education in Tanzania, as well as how linguistic devices are used in Swahili literature and political discourse.