In Spain, the origin of the CLIL methodology began at the Primary education level thanks to two programmes. The former, known as the MEC/BC Bilingual Project, was an agreement signed between the Spanish Ministry of Education (MEC) and the British Council (BC) in 1996. The latter, known as the CAM Bilingual Project, was launched by the Comunidad Autónoma de Madrid (CAM) in the academic year 2004-2005. Two decades have passed since the implementation of the MEC/ BC Bilingual Project and one decade since that of the CAM Bilingual Project. The editors of CLIL for teachers: From theory to practice firmly believe this is an excellent moment to reflect on the CLIL approach to L2 teaching.