This chapter looks at the current purposes and design of school readiness assessments and examines factors that affect their effectiveness, including the content and administration of the tests, how they relate to wider assessment practices, and the impact the practitioner can have on the process and outcomes. The chapter draws on a range of international approaches and practices to discuss the limitations of current processes and suggests that these need to be reconsidered, with school readiness being recognized as a process not a one-off event.