The use of test scores as a performance measure in high-stakes educational accountability has become increasingly popular since the enactment of the No Child Left Behind Act of 2001 (NCLB), which imposed sanctions such as the threat of losing federal funds unless a state implemented a school accountability system that measures student progress continuously. Since then, many in the education community have questioned whether differences in student test scores reflect actual discrepancies in the long-term well-being of individuals. In this review, we try to address this question in the light of the extant literature that examines the relationship between test scores and later life outcomes. We show that while there are certainly studies that contradict the causality of this relationship, there is also abundant evidence suggesting a causal link between test scores and later life outcomes. We conclude that any debate about the use of test scores in educational accountability (1) should be framed by use of all relevant empirical evidence, (2) should also consider the predictive validity of nontest measures of student success, and (3) should keep in mind that the predictive validity of test scores could be stronger in some contexts than others.