This book focuses on teaching English as a FL to young learners in the Primary school. Set within a Vygotskian framework, it describes a longitudinal classroom-based research project carried out in Spain with children aged between 8 and 10. After reviewing related literature from the fields of SLA and educational psychology, the teacher-student interaction is analysed on two different levels: Firstly, an Activity Classification System designed by the authors is used to trace the development of the classroom activity within topic-based units and secondly, a more finely-grained analysis of the discourse reveals the different types of strategies through which the teacher mediates and guides the children's learning. This book is of interest to EFL teachers, teacher trainers and student teachers at the primary level, since it offers both theoretical reflection and methodological insights for all those involved in teaching English to children.