This Element reviews the key foundational concepts, beliefs, and practices underpinning approaches to assessment in English Language Teaching. Exploring major concepts and practices through educational, social, and ethical perspectives, it offers theoretically informed and close-to-practice descriptions and up-to-date explanations of the affordances and limitations of different assessment approaches related to language teaching. This Element presents a cohesive and pragmatic framework that allows teachers to efficiently implement tests and assessments in their contexts.