Background: International large-scale assessments (ILSAs) are a much-debated phenomenon in education. Increasingly, their outcomes attract considerable media attention and influence educational policies in many jurisdictions worldwide. The relevance, uses and consequences of these assessments are often the focus of research scrutiny. Whilst some argue that the assessment outcomes provide an effective basis for informed policy-making, critics claim that the use of international assessment data can result in a range of unintended consequences, such as the shaping and governing of school systems "by numbers." Purpose: This article explores and analyses the arguments about the uses and consequences of ILSAs. In particular, the discourse about the assessments' consequential validity will be discussed and evaluated. Sources of evidence: Literature relating to the uses and consequences of large-scale assessment was analysed, with a focus on research on the consequential aspects of validity. Main argument: Much research suggests that ILSAs have unintended consequences that affect and influence educational policy. However, the influences on educational policy are complex and interwoven: for example, it is not clear-cut whether effects such as converging curricular are, necessarily, direct consequences of large-scale assessments. Further, it is suggested that a beneficial consequence of large-scale assessment is the infrastructure they provide for studies in the social sciences, although caution must be applied to causal claims, in particular because of the cross-sectional design of the assessments. Conclusions: The considerable literature discussing the uses and consequences of large-scale assessments tends to point out potential negative aspects of the studies. However, it is also apparent that large-scale international assessments can be a valuable resource for studying global trends and evolving systems in education. Despite the extensive debates around large-scale assessment outcomes both in the media and in educational policy arenas, empirical educational research all too often appears underused in the discussion.