An important issue in (language) education is how content-based learning provides opportunities for academic language learning. This is particularly relevant for Flemish (Belgian) second language learners or other 'vulnerable learners' who have difficulty in acquiring the language of schooling. Teachers are often at a loss when trying to bridge the gap between students' current language proficiency and the targeted academic language skills. However, research shows that teachers do? make a difference with respect to academic language and literacy development especially for vulnerable learners. This presentation focuses on how teachers can make this difference by looking at the characteristics of powerful language learning environments for all students in all lessons, and by exploring how teachers and students can co-construct meaning (both content and language) and develop their literacy skills. The quality of classroom discourse and functional literacy tasks as well as the participation and engagement of students are key factors in determining students' language learning opportunities. The presentation will be based on PhD research into second language development and knowledge construction in primary schools (Van Gorp 2010) and on research into functional and academic literacy in secondary schools (Goossens, Padmos, Vandommele & Bogaert 2011) at the Centre for Language and Education.