"This book is a guide for teachers of a second language (L2), particularly English, whose aim is to develop their career in Spanish formal secondary education. It is a practical approach to the state of the art in L2 teaching and learning nowadays, meant to provide the reader with sound teaching principles and examples of good practices, based on our own experience as L2 teachers and teacher trainers. Its main audience is teachers in preparation and novice teachers just beginning in the profession, who can read this on their own or in the context of a pre-service training course. It may also be of use for practising teachers who want a hands-on introduction to the current state of L2 teaching and learning, because it is grounded on a solid empirical and theoretical background. We hope that by reading this book, teachers will be equipped with the rudiments of the profession so that they can adapt these principles and examples to the individual needs of their students and become successful mediators between materials, syllabi and the students themselves.