This monograph explores Content and Language Integrated Learning (CLIL) as a dynamic educational approach that combines language acquisition with subject content instruction. It presents a comprehensive synthesis of theoretical foundations, international and local teaching practices, and empirical research findings. The study examines key pedagogical principles of CLIL, its benefits and challenges, and the roles of teachers and learners in multilingual environments. Drawing on recent scholarly sources and field data, the monograph offers methodical recommendations for effective CLIL implementation in secondary education, contributing to the development of bilingual competence and subject literacy.