Our contribution presents the first results of a research project on the acquisition of Dutch and English intensifying constructions by Belgian French-speaking secondary school pupils. This study forms part of a broader interdisciplinary project on Content and Language Integrated Learning (CLIL) in French-speaking Belgium. CLIL classrooms provide greater input frequency of the foreign language than traditional education. Comparing the two education systems allows us to measure the impact of foreign language input on L2 acquisition in general, and on intensifying constructions specifically. From a constructional perspective (cf. Tomasello, 2003; Goldberg, 2010), foreign language acquisition is presumed to be more complex than L1 acquisition because of the competition between the specific constructions of the foreign language with the L1 constructions (Ellis & Cadierno, 2009), which can lead to “constructional transfer”. We can thus hypothesize that French-speaking learners of Dutch and English will i) underuse typical Germanic means of intensification such as ‘elative’ compounds [<N> [ADJ]]ADJ (e.g. ijskoud/ ice-cold) (Hoeksema, 2012) and ii) overuse syntactic constructions frequently used in French, like adverbial modification [[ADV] [ADJ]]AP (e.g. tout rouge, ‘completely red’) and adjectival reduplication [[ADJ] [ADJ]]AP (e.g. rouge rouge ‘completely red’) (Riegel, Pellat, & Rioul, 1994: 620, 622). As CLIL programs can be considered closer to L1 acquisition because of their inherent usage-based approach, we can also expect a more native-like acquisition of intensifying constructions by CLIL pupils. To test these hypotheses, we analyse the language productions of 378 5th graders in French-speaking Belgium: 198 CLIL learners of Dutch or English, and 180 learners of Dutch or English in non-CLIL education. We compare the results to similar productions by Dutch and English native speakers. Each group carries out two (already piloted) tests (Authors, 2015): the first one consists of a ...