Existing research concludes that diglossia between languages is a barrier to minority language use in health, social care and criminal justice settings. In addition, it concludes that more fulsome service provision is the key for promoting greater minority language use in such settings. Using the case of Welsh speakers in Wales as an exemplar, this paper explores what is known about minority language use in service settings and how that knowledge has been acquired. It is argued that the existing research has neglected the influence of interviews on accounts of minority language use. Moreover, it is argued that an important issue in promoting minority use in service settings is recognising and addressing the diglossia that can come to exist within a minority language once its use is institutionalised in such contexts. (Contains 2 notes.)