Book excerpt: Learning English as a foreign language in any formal education context requires opportunities for learners and teachers to give and receive feedback on the teaching learning process as it is happening. These opportunities could be created via various in-class activities specifically designed for this purpose. Teachers who create and use these diagnostic opportunities effectively detect what learners need in a timely fashion, and provide remedial teaching in the right time and mode, so that chances can be created for learners to improve their learning. There is no one universally accepted way of how to do this, however, with various approaches for collecting, analyzing and reviewing data for this purpose. This book encapsulates the unbreakable relationship between teaching, learning and assessment through a range of articles which scrutinize assessment from a wide spectrum, ranging from the role of assessment in language learning to ELT teacher assessment literacy, from the use of technology in classroom-based assessment to practicing teachers’ reflections on their teacher classroom action research, and from the role of the Common European Framework of Reference for Languages (CEFR) to empirical data analysis.