With the advent of bilingual programs in the Spanish education system and its growth in the international panorama, it is deemed essential to provide future generations of teachers with a solid basis of theory-practice nature in the target language, which in this case will be English. Therefore, the present book aims to unite in a synthetic way, throughout its 12 chapters, the different language acquisition theories, methodologies, resources, techniques, as well as activity design and sequencing for its implementation at schools. With every point being dealt in a progressive and systematic way, this book strives to ensure that the teaching practice is supported from theoretical foundations. In this vein, and in an attempt to upgrade the teaching and learning practice, and thus go along the lines of the current education system, this book hinges on providing readers, who are already (or on their way) specialized in Early Years education, with the know-how and expertise necessary for its subsequent implementation in the classroom, with all the pedagogical guarantees expected from a rigorous academic formation that meet the current curricular demands.