The assessment process is characterised as a cycle involving elicitation of evidence, which when interpreted appropriately may lead to action, which in turn, can yield further evidence and so on. An assessment is defined as serving a formative function when it elicits evidence that yields construct-referenced interpretations that form the basis for successful action in improving performance, whereas summative functions prioritise the consistency of meanings across contexts and individuals. Aspects of the interplay of meanings and consequences are explored for each of the three phases, and it is suggested that this interplay may be fruitful in distinguishing the two functions. Tensions between summative and formative functions of assessment are illustrated in the context of the National Curriculum, and although it is shown that such tensions will always exist, it is suggested that the separation of the elicitation of evidence from its interpretation can mitigate that tension.