On the emergence of bilingual code-switching competence*

Code-switching among pro®cient adult bilinguals has been extensively studied, and it is by now universally concluded that intra-sentential code alternations are rule-governed and systematic, displaying dependency relations that re ̄ect the operation of underlying syntactic principles. The central, guiding question to be addressed herein is whether and, if so, how second language learners acquire the knowledge that de®nes structural coherence and allows them to render wellformedness judgments for code-switched forms. This exploration takes on particular signi®cance given that learners receive no evidence which could guide them in rendering such judgments, and therefore results consistent with those observed among competent bilinguals could be imputed to unconscious, abstract linguistic knowledge. The investigation thus proves doubly fruitful, in the discovery of developmental patterns and in the evaluation of linguistic-theoretical methodologies and constructs.