This monography provides a comprehensive insight into the overriding hot topics regarding the implementation of bilingual education type CLIL (content and language integrated learning) that have been recently spotlighted by researchers and different stakeholders, including families and students. The authors analyse the multiple faces of CLIL as a global and ecological phenomenon and examine the potential of CLIL to guarantee effective language learning, along with preservation of adequate levels of content acquisition and satisfactory development of the mother tongue. The role of pre-service and in-service teacher training in unfolding CLIL is scrutinized, among other burning issues such as egalitarianism and sustainability of the approach.