The role of interaction in learning and the opportunities it provides for language learners are strongly emphasized in the literature. Unfortunately, classroom research on interaction has focused on the productions of students in the classroom, yet it has been argued that intrapersonal mental processes such as perceiving should also be considered in order to have a deeper understanding of classroom activities''effectiveness, and desired learning cannot be accomplished without understanding how students interpret the activities they are involved in. In the literature, the studies on the perceptions of students and teachers about interaction have not been conducted in a comparative manner to explore whether there is a relationship between the language proficiency level of the students and their perceptions. There is need, therefore, for research explaining and comparing the perceptions of teachers and EFL students of various language proficiency levels towards the interaction types and activities carried out in the classroom. In this respect, this book aims to satisfy this need and shed light on classroom interaction for ELT researchers and practitioners.