Harbert's main interests center around the syntactic structures of the Germanic languages (especially the older ones) and the Celtic languages (primarily Welsh and Scottish Gaelic), and what they can tell us about the principles of syntactic organization operating in natural language. He also has a developing interest in aspects of the phonology of these languages. His research is carried out within the general framework of Government-Binding Theory. Problems on which he has worked recently include apparent cross-linguistic and historical variation in the syntactic domain of anaphor binding, relative constructions, the syntax of negation and the syntax of agreement and case assignment. Harbert's publications include a systematic construction-by-construction comparison of the grammatical structures of both the modern and premodern members of the Germanic language family. In addition, he has developed an interest in language endangerment and minority language issues.
- Harbert, W., to appear (2007). The Germanic Languages. Cambridge University Press.
- Harbert, W. 2002. The Syntax of Indefinite Phrases in Negative Sentences in Germanic. The Interdisciplinary Journal of Germanic Linguistics and Semiotic Analysis. 7: 101-126.
- Harbert, W. 2002. A Preliminary Look at the State of Welsh Language Teaching in America." Journal of Celtic Language Learning, vol 7. 2002.
- Harbert, W. and Maher Bahloul. 2002. Postverbal Subjects in Arabic and the Theory of Agreement. in U. Shlonsky and J. Ouhalla, eds., Themes in Arabic and Hebrew Syntax. Kluwer.
- Harbert, W. 1999. Erino Portun ih Firchnussu. in Gerald Carr, Wayne Harbert and Lihua Zhang, eds., Interdigitations: Essays for Irmengard Rauch. Peter Lang.
- Harbert, W. (1997). Underspecification and the Old High German monophthongization. In I. Rauch and G. Carr (Eds.), Insights in German Linguistics II . Mouton de Gruyter.
- Harbert, W. (1995). Binding theory, control and pro. In G. Webelhuth (Ed.), Government binding theory and the minimalist program . Blackwell.
- Harbert, W. & Bahloul, M. (1993). Agreement asymmetries in Arabic. Proceedings of the Eleventh West Coast Conference on Formal Linguistics . Stanford: CSLI.
- Harbert, W. (1992). Gothic relative clauses and syntactic theory. In I. Rauch (Ed.), On Germanic linguistics: Issues and methods . Mouton de Gruyter.
- Harbert, W. (1990). Binding, SUBJECT and accessibility. In R. Freidin (Ed.), Principles and parameters of comparative grammar. Cambridge, MA: MIT Press.
- Harbert, W. & Pet, W. (1988). Movement and adjunct morphology in Arawak and other languages. International Journal of American Linguistics .