The year-end passage and signing of the Every Student Succeeds Act represents more than just a rare bipartisan agreement on the part of the nation’s chronically polarized policymakers. For the first time in more than a decade—and a half-century after enactment of the country’s main K-12 law—Congress has redefined the federal role in elementary and secondary education. And it’s done so in a way that aims to enhance the authority of states and school districts that had long chafed at the strictures of ESSA’s predecessor, the No Child Left Behind Act. Now comes the really hard part: implementation. This special report on ESSA looks at what the law will mean for virtually every aspect of public schooling when it takes full effect in the 2017-18 academic year. Topics include accountability and testing, teacher quality, research, regulation, funding, early-childhood education, and thorny issues involving student groups that often lag behind their peers.