This book explores second language (L2) learning, teaching and assessment from a comprehensible input (CI) perspective. This focus on the role of input is important for deepening our understanding of interactions between the learner, teacher and the environment as well as of the nature of the learning, teaching and assessment processes. The book takes a blended approach that promotes the intertwining of theory, research and practice in L2 pedagogy and assessment and aims to address the commonly used concept of CI and its role in L2 education. Content includes a comprehensive discussion of the conceptual foundation of CI; a multimodal and dynamic interpretation of CI from numerous perspectives; a critical discussion of well-known L2 acquisition theories and research; a practical examination of the role of multimodal forms of CI in L2 pedagogy; an analytical review of factors to be considered when modifying CI for pedagogical purposes in different settings and an overview of CI in L2 assessment. It will be of interest to students in the fields of L2 learning, teaching and assessment, teachers in second/foreign language settings and researchers of SLA and teacher education.