This study investigates the use of pronounsnousand a subgroup ofonin a corpus of advanced oral and written French interlanguage produced by 32 Dutch L1 speakers. The subjectnous+ first person plural verb is characteristic of formal styles whileon+ third person singular verb is typical of informal styles. A quantitative analysis of the oral corpus revealed that the amount of authentic interaction, but not the amount of formal instruction, in the target language is significantly related to the choice ofon. Its use correlated with morpholexical accuracy rates, fluency, omission ofnein negations and use of colloquial vocabulary. A similar analysis of the written corpus revealed equal proportions ofon, which suggests that as a group, the learners had not yet completely acquired the constraints on this variable.