The author asserts that there is only one fundamental purpose of assessment in education. When this single purpose is recognised and taken as the starting point for thinking about assessment, it becomes a unifying rather than fragmenting influence in the field. He states that the fundamental purpose of assessment in education is to establish and understand where learners are in an aspect of their learning at the time of assessment. There is no other purpose. Establishing where learners are in their learning usually means establishing what they know, understand and can do. When this single purpose is appreciated, many invented distinctions become less conceptually fundamental and some concepts can be approached in new and more useful ways.