Bilinguals dynamically activate lexical items in one or both languages depending on a number of factors. We explored the interaction effects of semantic constraints, language context, and L2-proficiency on cross-language interaction and switch costs in bilinguals who habitually codeswitch between Algerian Arabic (AA) and French. We recorded response times to French cognates and non-cognates embedded in auditory AA or French sentences. High proficiency bilinguals could restrict selection to the target language regardless of the language context. In lower proficiency bilinguals, however, selection was specific to the target language in non-switching contexts but was nonspecific in switching contexts where cross-language interaction yielded inhibitory and facilitatory cognate effects. Results of this study therefore suggest that lexical selection in codeswitching bilinguals is dynamic and is dependent on proficiency, semantic constraints and language context. This within-subject study using auditory stimuli contributes towards a more ecological methodology in investigating sentence processing in codeswitching bilinguals.