This book intends to look into CLIL teaching professional practice through the prism of reflection. It offers a comprehensive coverage of a CLIL teacher’s features, their attitudes to the approach, teaching methodology, assessment, materials development, cooperation with other CLIL and non-CLIL teachers, professional development, expectations and beliefs. Furthermore, it focuses on CLIL teachers’ positive and negative emotions experienced in relation to CLIL. As a CLIL trainer I spend a lot of time with CLIL teachers trying to guide them in the process of teaching in CLIL but also to help them face many challenges and overcome obstacles which often discourage them from working in the CLIL environment. Being greatly inspired by the ongoing research in the field but also by my CLIL trainee teachers I felt there was a need to conduct such research and make the reader reflect on his/her own teaching experiences in CLIL.