The aim of this paper is to present the socio-linguistic framework of Basque-Gascon bilingualism in Lower Navarra (more exactly in the Pays de Mixe). The prolonged bilinguism has not brought about the substitution of Basque by the Romanic language which surrounded it. On the socio-linguistic plane at least, it can be said that Gascon has played the role of a buffer between Basque and French. In this study, the linguistic consequences of this contact are dealt wlth, which are not limited to lexical loans and which are interesting because the big of the typological distance which separates both languages.