For years, the debate about American education was like a bad marriage. The arguments were about everything but the core issue--instructional quality. The other issues--education finance, school choice, standards--all matter, but are secondary to the importance of effective instruction. In the labor-intensive education field, effective instruction is nearly synonymous with teacher effectiveness. Trying to improve the quality of education in America without addressing teacher effectiveness is the same as trying to improve a baseball team without paying attention to hitting and fielding. Yet despite clear evidence about how much teachers matter, this is largely what American education tried for much of the 20th century. That all changed quickly in the late 1990s and the aughts. Suddenly teacher quality emerged as a focus of national policymakers. New organizations launched and others made teacher quality a priority. The emphasis was so intense that it prompted a backlash, with some advocates decrying a "war on teachers." The pivot bemused researchers, who for decades had identified teacher effectiveness as the most important in-school factor affecting student achievement. And not surprisingly, as policymakers rushed to close the gap between research and practice, they made mistakes and over-corrections--the predictable and common problems of any significant public policy pivot. Except these policy changes affected America's teachers. Teachers hold a conflicted place in American public life. They are at once individually beloved community figures tackling a difficult and important job and collectively among the most powerful interest groups in American politics. When policymakers began taking a serious look at teacher quality, the stage was set for a political battle that continues now at the national, state, and local level. The story of this change is incomplete. It's playing out in schools and statehouses around the country. It's also full of puzzles and questions, some of which are beyond the scope of this paper. Because teacher effectiveness is so important, why did policymakers wait so long to take it on? If the answer is because teachers' unions are so powerful, then why did change happen when it did--and under Democratic as well as Republican presidents and governors? What role did philanthropy play in driving these changes? Substantively, how much change has actually happened, or are we seeing old policy wine in shiny new bottles? Are the changes championed during the past few years likely to improve student learning? Are they even the optimal approaches for a field colliding with technology, evolving parental preferences, and a changing society? This paper seeks to take an early look at some of those questions. It traces the changes since the late 1990s and attempts to capture a rapidly evolving status quo and make recommendations for next steps. It's based on the authors' research and analysis of existing literature, experience working directly on these issues in the public and nonprofit sectors, and interviews with experts, policymakers, researchers, philanthropists, and practitioners who played key roles leading teacher quality to where it is today.