The multicompetence hypothesis (Cook, 1991, 1992, 1993) raises two related questions: (1) whether very advanced L2 learners have the same intuitions of grammaticality as native speakers; and (2) whether differences between these learners and native speakers are due to the two grammars influencing each other. Middle constructions in English and French provide a useful probe for exploring these issues since they are much more limited in English than they are in French. I developed two grammaticality judgement tasks, one in English and one in French, based on differences between the two languages vis-à-vis middle constructions. They were administered to Anglophones and Francophones who were advanced and very advanced learners of their L2, as well as to unilingual groups with the same L1s. The results showed that the advanced and very advanced learners’ judgements differed from those of the unilinguals. The differences between their responses suggest that knowledge of two languages affected their judgements, although transfer cannot account for all of the differences. The results lend further support to a previous research finding that L2 learners are conservative in their judgements of grammaticality.
