He is well known for his work on Welsh syntax and phonology and on topics in the general theory of grammar, such as the nature of clitics, the semantics of mood, and the notion of grammatical dependency. He has published extensively on the languages of Wales and Brittany and has given invited lectures at many universities and conferences in Europe and North America.
He has been the Vice-President of the Philological Society of Great Britain and editor of its Proceedings. He is also the President of the Celtic League, an international organisation that campaigns for the rights of Celtic nations and peoples.
He was born on 15 February 1950 in Carmarthenshire, West Wales. He studied Welsh language and literature at University College, Swansea and then took an M.A. degree in linguistics at the University of Wales, Aberystwyth. He went on to complete a PhD in linguistics at the University of Reading.
He has held academic posts at the University of Wales, Aberystwyth; the University of Oxford; the University of Manchester; and the University of Michigan, Ann Arbor. He was appointed Professor of Linguistics at Bangor University in 1992 and became Dean of the Faculty of Arts and Social Sciences in 2004. He retired from his posts in 2012 but continues to work as Emeritus Professor.
In addition to his academic work, Mark Gwynne Jones has been active in promoting the Welsh language and culture. He is a former Chairman of the Welsh Language Board and a former President of the Welsh National Eisteddfod. He is a member of the Gorsedd of Bards, an ancient Welsh cultural institution, and has been awarded the Gorsedd's Gold Medal for his contribution to Welsh literature and culture.