The Key Stage 2 Reading Standard Assessment Test (SAT) is a national test of reading comprehension taken by all 11-year olds in state schools in England. The results of this high-stakes test are used for accountability and comparative purposes. While it is acknowledged that these uses have a negative impact on both schools and pupils [Education Commons Select Committee. 2017. "Primary Assessment." Accessed July 29, 2019. https://publications.parliament.uk/pa/cm201617/cmselect/cmeduc/682/682.pdf.], less attention has been paid to the validity of the test itself. This article presents a conceptual framework which views assessment as a generic staged process. The framework highlights specific issues related to validity that need to be considered at each stage of the assessment process. When applied to the KS2 Reading SAT this framework shows the test to be of questionable validity and value. Alternative approaches are suggested.