His main academic interests are proper names (both from the historical and the theoretical perspective), historical linguistics in general, the philology of the Germanic, Romance and Celtic languages, regional variation in language, and local history. He is editor of the Survey of English Place-Names for Hampshire and was principal investigator of the AHRC-funded project Family Names of the United Kingdom (FaNUK), running from 2010 to 2016, of which Patrick Hanks was lead researcher.
He has written books on the names of the Channel Islands, the local place-names of St Kilda, Hampshire and Sussex, the dialect of Sussex, and, with Andrew Breeze, on Celtic place-names in England, as well as over 500 academic articles, notes, and collections on related topics. His main contribution to linguistic theory is The Pragmatic Theory of Properhood, set out in a number of articles since 2000.[1][2][3][4]
He is also the author of Word Structure, a student's introduction to linguistic morphology (Routledge), and of online resources on Shakespeare's character-names and on the place-names of Hayling Island.
Books, dissertations and selected other freestanding publications
1977 The status of rules in historical phonology. Doctoral dissertation 10301, University of Cambridge. [Unpublished.]
1987 (co-ed. with John Lyons, Margaret Deuchar and Gerald Gazdar) New horizons in linguistics 2. Harmondsworth: Pelican; pp. viii + 465 (ISBN978-0-14-022612-6).
1988 Toponymic topics: essays on the early toponymy of the British Isles. Brighton: Younsmere Press; pp. v + 124 (ISBN0-9512309-1-3).
1989 The place-names of Hampshire. London: Batsford; pp. vii + 193 (ISBN0-7134-5625-6).
1991 The ancient and modern names of the Channel Islands: a linguistic history. Stamford: Paul Watkins; pp. xiv + 144 (ISBN1-871615-15-1).
1992 (ed.) De A.B.C. psalms by Jim Cladpole (James Richards). Brighton: Younsmere Press; pp. 46 (ISBN0-9512309-6-4).
1993 Hampshire place-names. Southampton: Ensign Publications. Paperback edition of The place-names of Hampshire; pp. 193 (ISBN185455 090 X).
1996–2007 (ed.) Locus focus: forum of the Sussex place-names net (7 vols, 14 issues).
1999 The place-names of West Thorney. Nottingham: English Place-Name Society (supplementary series 1); pp. v + 64 (ISBN0904889 52 1).
1999 Word structure. London and New York: Routledge (Routledge Language Workbooks); pp. ix + 101 (ISBN0 415 20631 6). [Student guide to morphology. Also available as an e-book from 2005.]
2000 (with Andrew Breeze; including a contribution by David Horovitz) Celtic voices, English places: studies of the Celtic impact on place-names in England. Stamford: Shaun Tyas; pp. xiv + 433 (ISBN1-900289-41-5).
2006 (guest ed.) Name theory. Special issue of Onoma, vol. 41 (spine date 2006; appeared 2011); pp. 309 (ISSN0078-463X, eISSN 1783-1644).
2010 A place-name history of the parishes of Rottingdean and Ovingdean in Sussex (including Woodingdean and Saltdean). Nottingham: English Place-Name Society (Regional series 2); pp. xviii + 222, ISBN978-0-904889-84-0. [Published with the aid of a grant from the British Academy.]
2010 The traditional dialect of Sussex: a history, description, selected texts, bibliography and discography. Lewes: Pomegranate Press; pp. 349. (ISBN978-1-907242-09-0.) [Published with the aid of a grant from the Marc Fitch Fund.]
2016 (co-ed. with Patrick Hanks and Peter McClure) The Oxford dictionary of family names in the United Kingdom. Oxford: Oxford University Press. (ISBN9780199677764; also ebook and online versions.)
2017 Wilkins of Westbury and Redland: the life and writings of the Rev. Dr Henry John Wilkins (1865-1941). Bristol: Avon Local History Association pamphlet 24.
2017 Your city's place-names: Brighton and Hove. Nottingham: English Place-Name Society. (ISBN9780904889970.)
2017 Your city's place-names: Bristol. Nottingham: English Place-Name Society. (ISBN9780904889963.)
2019 Places, names and history in north-west Bristol: Shirehampton, Avonmouth and King’s Weston. Bristol: Bristol Centre for Linguistics, University of the West of England.
2019 Your city's place-names: Cambridge. Nottingham: English Place-Name Society.
^Coates, Richard (2006). "Some consequences and critiques of The Pragmatic Theory of Properhood". Onoma. 41: 27–44.
^Coates, Richard (2007). "A strictly Millian approach to the definition of the proper name". Mind and Language. 24 (4): 433–444. doi:10.1111/j.1468-0017.2009.01369.x.
^Coates, Richard (2012). "Eight issues in The Pragmatic Theory of Properhood". Acta Linguistica Lithuanica/ Lietuvių Kalbotyros Klausimai. 66: 119–140.