Why has the modern era of American education reform been such a disappointment? Why has a nation so dedicated to improving its schools continually pulled up short, year after year, embracing weak reforms unsuited to the challenge and refusing to throw off the shackles of the past? The answer comes down to simple fundamentals that have long been staples of political science: vested interests, checks and balances. The vested interests in this case are the teachers unions, which are by far the most powerful groups in the politics of education. And their power is magnified by the American system of checks and balances—which, quite by design, creates veto points that make it exceedingly difficult for reformers to get major new legislation passed and correspondingly easy for opponents to block. The teachers unions have been masters of the politics of blocking for the past quarter century. Major reform is threatening to their vested interests in the existing system, and they have used their formidable power—leveraged by checks and balances—to repel, weaken, and render ineffective the efforts of reformers to bring real change. This is the basic story of the modern reform era. The rest is detail.