- Euromosaic (1993). Project financed by the European Union. Research on the social situation of European Minority Languages, in order to design a new language policy for EU. I was co-director and co-coordinator of the quantitative phase in Galicia. (The data derived from this field work has been used by the European Union in various publications.)
- The Attitudes of Consumers towards the Use of Galician Language in Advertising and Commercial Relationships. (1995–1997). Financed by the Council for Galician Culture. Co-director of the project.
- Sociolinguistic Map of Galicia (1990–1996). Research Project entrusted by the Galician Government (Department of Education) to Real Academia Galega’s Seminar of Sociolinguistics. (Four volume publications arising from this; see # 4, 6, 7, 8 under “Books”.)
- Developing Policy Linkages between Language Production and Language Use. Project financed by the European Union’s General Direction XXII (The Seminar of Sociolinguistics was the responsible partner in Galicia). 1997.
- Construction of a Computerized Galician-Spanish Bilingual Speaking Corpus (1999-2002). Research Director: Prof. Dr. Xoán Paulo Rodríguez Yáñez. Project financed by the University of Vigo and the Galician Government.
- Quantitative survey regarding the creation of a permanent section on Galician Studies at the Modern Language Association. This online survey aims to investigate the reasons for academics in North America and worldwide to endorse this petition, as well as their opinions and attitudes of academics on Galicia and Galician Studies. A study and different publications will follow. UW-Milwaukee Galician Studies Research Group. Rei-Doval is the PI. Data collected in Fall 2013. 2013-present. http://www4.uwm.edu/letsci/spanish/research/galician/upload/MLAGalicianStudies-QualtricsSurvey.pdf
- Contacto e cambio lingüístico en galego [Language contact and change in Galician]. Research project, in collaboration with the Instituto da Ligua Galega, funded by the Spanish Government Ministerio de Economía y Competitividad, 2016-2019.
- Contact, linguistic change and ideology in linguistic minorization contexts. Research fellow in the project, funded by the Spanish Government, Ministerio de Economía y Competitividad. 2020-2024. Project Code PID2019-110352GB-I00, MCIN/AEI/10.13039/501100011033.