This study will provide a contrastive analysis of comparative constructions in French and English, on the one hand, and investigate the acquisition of these constructions by French-speaking learners of English in French-speaking Belgium, on the other. A difference will be made between pupils following the Content and Language Integrated Learning (CLIL) method and pupils enrolled in the traditional language learning settings. CLIL is one of the leading didactic methods to have been developed to promote multilingualism through education in Europe (Hiligsmann et al., 2017). This approach involves the teaching of content school subjects through the medium of a target language distinct from the school’s mainstream language (Eurydice, 2012). Although the CLIL method has been extensively documented internationally (Ruiz de Zarobe,2008; Rumlich, 2016; Seikkula-Leino, 2007), its impact on second language acquisition remains a subject of scholarly debate. Assessing the impact of CLIL is the purpose of an ongoing large-scale longitudinal and interdisciplinary research project in French-speaking Belgium. This particular study will contribute to this line of research by contrasting the use of comparative constructions in native French and native English and by investigating the CLIL and non-CLIL pupils’ use of English comparative constructions. We first investigate the similarities and differences between French and English through a contrastive analysis with comparative constructions as a tertium comparationis. We base this analysis on the description of French and English ‘ordinary’ comparative constructions, illustrated in (1-3), in grammars by Biber et al.(1999), Grevisse (1975), Riegel et al. (1994) and Quirk et al. (1978), leaving aside ‘idiomatic’ comparatives such as the construction may/might as well (Sawada, 2007). This type of construction has been extensively studied within the frameworks of syntax and semantics (Bresnan, 1973; Fuchs et al., 2008), and cognitive or functional typology (Andersen, 1983; ...