Abstract
This article examines syntactic variation in relative clause (RC) constructions in Mundaka Basque among two groups of Mundaka Basque speakers. The language of instruction the Mundaka Basque speakers had in school draws the line that separates the two populations: the first group (Mundaka Basque I) had Spanish as the language of instruction and no Basque as a subject, while the second one (Mundaka Basque II) had Standard Basque as the language of instruction and Spanish as a subject. The results of an experiment involving a cloze test show that differences in production between these populations depends on the grammaticality of RCs with an indirect object or adjunct gap and a subject or direct object RC head: for Mundaka Basque I relativization under this configuration is grammatical, while for Mundaka Basque II, it is not. This variation is due to simplification of relativization accessibility in Mundaka Basque II caused by Standard Basque.