Content and Language Integrated Learning (CLIL) is a dual-focused educational approach in which an additional language is used for both the learning and teaching of content and language. The term was coined by David Marsh in 1994 and gained traction primarily in European education policy, becoming a cornerstone of the European Commission's multilingualism strategy.
Do Coyle (1999; elaborated in Coyle, Hood & Marsh, 2010) proposed the 4Cs as a planning and analysis framework for CLIL:
The 4Cs are interdependent: effective CLIL integrates all four simultaneously rather than treating them sequentially.
CLIL is not simply immersion by another name. In immersion (e.g., Canadian French immersion), language learning is incidental to content. In CLIL, both language and content have explicit learning objectives. CLIL teachers are expected to attend systematically to the language demands of their subject, scaffolding academic literacy rather than assuming it will develop through exposure alone.
CLIL demands significant teacher competence in both subject and language, which creates training challenges. Critics note that without careful language scaffolding, CLIL risks becoming "content teaching in L2" with limited language development, the so-called "language thinning" problem.