This article analyses how studies on regional Frenches identify the phenomenon studied and how knowledge is elaborated. It addresses the issue of the relationship between ideological choices and the theoretical and methodological options of the field. It explains why scholarship in the field has not been able to theorise adequately with regard to the diffusion of a language in diverse multicultural and multilingual contexts. A comparison between this approach to regional Frenches and research conducted in the Indian Ocean on other aspects of regional Frenches, especially morpho-syntax, using another conceptualization of sociolinguistic variation, shows to what extent the field can benefit from a renewed approach. The article also illustrates the pitfalls of studies which do not question the epistemological foundations upon which scientific knowledge is built.