Accountability has been a central feature of educational policy in a number of states since the 1990s. In part because of the perceived success of accountability in the states where it was initially tried, federal law introduced mandatory reporting and accountability through the No Child Left Behind Act of 2001. Yet not everybody is happy with school accountability. Its opponents continue to aggressively search for evidence that testing and accountability do not work—or, better, that they are actually harmful. The hope of the anti-accountability forces is that they can stop testing before it is fully in place and before rollbacks would be impossible.