CLIL (Content and Language Integrated Learning) is a recent teaching approach widely adopted in numerous international contexts, especially in Europe where it was promoted as a way to promote language learning within the educational system. When implemented, CLIL predominantly involves subject content teachers using English to teach their subject. This has required the development of specific teacher education programs in Italy. This contribution illustrates how the teaching knowledge of both content and English language teachers is evolving as CLIL is implemented within Italian teacher education courses.