‘Evidence based policy' has sharpened the appetite for numeric data, and numbers of all manner are now embraced by and folded into education policy and politics. But even as policymakers encourage and depend upon this intertwining of science and politics, some scientists - assessment and measurement experts and statisticians - are squirming to struggle out of this embrace, uncomfortable with the interpretations and use of their data, which, they protest, are being stretched well beyond their epistemic warrant. In the US, the National Center for Education Statistics (NCES), part of the Department of Education and described as the ‘primary federal entity for collecting and analyzing data related to education,' is mandated to report ‘just the data,' without any policy inferences or recommendations, to the Department. This is to ensure that the NECS remains trustworthy and untainted by political agendas. The policy wing of the Department has its own statistical unit which can, one assumes, be more readily harnessed to lend support to policies the Department wants to pursue. This stance is in sharp contrast to the OECD, which collects and presents data with the express purpose of influencing policy. The OECD also actively spreads policy messages through the media and through presentations at conferences and to a variety of government agencies.Whether scientists are secluded from policy and politics, or subsumed by policy influencers, they find themselves watching from the sidelines as often unsupportable relations are described and unwarranted conclusions are drawn and used as rationale for policies. Frustrated by this, experts in measurement and assessment are beginning to extend the notion of validity to include the interpretation and use of data, and are speaking out with greater frequency and urgency in journals and conferences. Based on extensive interviews with thirty senior measurement experts and policy makers in the US and Australia, and located within the field of science and technology studies (STS), this paper explores the wrangling over science as it is currently being played out in the education policy arena in national and international forums. It suggests that the current contestations might provide a moment for reflection and intervention, and invites discussion on the nature and use of science, on the possibilities for interdisciplinary engagements in science and policy, and on the types of research agendas the education research community might confidently develop to inform policy making.