As part of a project on CLIL in French-speaking Belgium, this study aims to explore the impact of formal and informal input on learners’ variability in writing, and to compare two target-language conditions (Dutch and English) in CLIL and non-CLIL settings. A regression model shows that CLIL is a significant predictor of L2 outcomes for both target languages, but that the relative impact of formal and informal input differs depending on the target language. In short, the amount of formal language exposure predicts the outcomes of the English learners’ written productions, and the frequency of informal exposure those of the Dutch learners. We argue that this observation is likely related to the difference in status that each of these languages holds among the pupils in our sample. The findings thus highlight the importance of the L2 status in research on CLIL, since different L2s can yield different results