The chapter is characterising the two key purposes of assessment, formative and summative, and considering how they are related and can be brought together in developing a dependable approach to summative assessment using evidence collected and used in formative assessment. The third purpose of assessment, accountability, is dealt with as a special use of summative assessment. The range of approaches to using assessment formatively – to influence learning activities as they take place – and summatively, to record evidence of what has been learned at certain times, is discussed. Some examples from the ASSIST-ME project illustrate the variety of approaches to assessment and the overlapping relations between formative and summative use of assessment.