CLIL (Content and Language Integrated Learning) research has thrived recently. Yet, while more and more is learnt about the impact of CLIL on motivation, proficiency, and content learning, few investigations examine how CLIL influences students of different socio-economic status (SES) and why. The recent large-scale English Impact study conducted in the Madrid region showed that CLIL has a potential to limit the influence of SES on students' language learning motivation and proficiency. Yet being solely quantitative, it did not probe into the reasons behind such a result. This mixed-methods study aims to uncover such reasons. 138 teachers from different schools in the Madrid region filled in the TALIS questionnaire (OECD 2013. TALIS Teacher Questionnaire. http://www.oecd.org/education/school/TALIS-2013-Teacher-questionnaire.pdf) and further 20 teachers were interviewed. Whereas no significant differences between teachers from CLIL and non-CLIL schools were identified through the questionnaire, the interviews revealed that teachers from bilingual schools adapted their teaching methodology to best suit their students' needs, and were more willing to take risks than their counterparts in non-bilingual schools.