Despite an increase in ethnic diversity within the state, the Irish teaching workforce remains starkly mono-ethnic. This article is based on an analysis of data generated through a sequential explanatory mixed method research project involving questionnaire responses from 240 migrant teachers and subsequent focus group with a selection of teachers. Findings suggest that migrant teachers are slow to engage in the formal accreditation process, and face considerable challenges when they do. This reflects not only practical difficulties, but also narrow discourses of who can legitimately be recognised as a teacher in Ireland. This in turn is linked to cultural arbitraries highlighted through the research, such as a requirement to be able to teach through the Irish language in primary school and a requirement to be registered to teach in primary or post-primary schools only. In exploring these barriers, we draw broadly on Bourdieu and Passeron's (1990) work, which understands teachers as pedagogic agents, imbued with pedagogic authority through formal processes of accreditation and selection. These processes involve the imposition of cultural arbitraries which legitimate certain languages, content or stances over others. Recommendations include revisions to the registration process to take previous teaching experience into account.