This book addresses the main complementary theories and concepts related to teaching English as a foreign language. It offers a compilation of subjects written by five authors, who are experts in the diverse disciplinary areas and contents here explained. It comprises ten chapters that deal with interesting topics such as the bilingual person, English as a world language, contemporary trends in TEFL, European policies on language education, bilingual education and CLIL, the foreign language curriculum in secondary education in Spain (?), the EFL teacher in class, individual factors in TEFL and classroom language and management. Each chapter includes activities for further reflection as well as a glossary of the most relevant terms introduced.