In this article we examine the complex processes involved in small-scale ethnicity emergence and legitimation, and highlight the multi-dimensional elements present in moving from a strong regional identity to an externally legitimate ethnic group. We use Cornwall as a case study: administered as an English county, there has been a historic ethno-cultural movement for recognition alongside recent inclusion in national statistics; however, legitimation by external elites has been problematic. The first sections outline the Cornish as a group; we argue that however one conceptualises ‘ethnicity’, the people of Cornwall must constitute such a group. We examine the dichotomous effects of the interplay between strong regional assertion and a Cornish ethnicity more formally. In the latter sections we apply these arguments to broader sociological discussions around the legitimation of particular groups, and show that the Cornish are indicative of the wider theoretical literature. In conclusion, we assert that the Cornish are representative of the push/pull mechanisms felt acutely in any core/periphery power relations, and should be seen as central to emerging small-scale ethnic groups more generally.