This chapter examines the multiple purposes and functions of assessment so that an educational approach to assessment can be taken. It aims to help readers develop a conception of assessment that is focused on using assessment to improve the quality of teaching and the quality of learning. Because assessment is connected to curriculum, teaching, and learning processes, conceptions of assessment are influenced by how those processes are viewed. Becoming aware of how a person understands and relates to assessment matters since their conceptions filter and guide their interpretation and implementation of assessment. Studies of New Zealand high school student conceptions of assessment have shown that greater endorsement of both improvement and evaluation functions of assessment is associated with greater achievement. Failure to use assessment to improve school or classroom practices may come about because the leader has different conceptions of assessment than the teachers working in the school.