These would seem to be dark days for the school-choice movement, as several early champions of choice have publicly expressed their disillusionment. A few years ago, the Manhattan Institute's Sol Stern -- author of Breaking Free: Public School Lessons and the Imperative of School Choice -- caused a stir when he backed away from his once-ardent support. Howard Fuller, an architect of Milwaukee's school-voucher plan and the godfather of the school-choice movement, has wryly observed, "I think that any honest assessment would have to say that there hasn't been the deep, wholesale improvement in [Milwaukee Public Schools] that we would have thought." Earlier this year, historian Diane Ravitch made waves when she retracted her once staunch support for school choice in The Death and Life of the Great American School System. "I just wish that choice proponents would stop promising that charters and vouchers will bring us closer to that date when 100 percent of all children reach proficiency," she opined in her blog. "If evidence mattered, they would tone down their rhetoric." Harvard professor and iconic school-voucher proponent Paul Peterson has characterized the voucher movement as "stalled," in part by the fact that many "new voucher schools were badly run, both fiscally and educationally," and in part because results in Milwaukee were not "as startlingly positive as advocates originally hoped." Likewise, Peterson argues, "the jury on charter schools is still out." To many who hold out hope that choice can help fix what ails America's schools, these hedges and reversals have been startling. And yet, looking back, it is hard to see how they were not inevitable. For decades, school-choice advocates have seemed bent on producing this hour of disappointment. There has been, for instance, a tendency to vastly overpromise. In 1990, the same year that Milwaukee's tiny voucher program launched the school-choice debate, scholars John Chubb and Terry Moe argued in their seminal volume, Politics, Markets, and America's Schools: "Without being too literal about it, we think reformers would do well to entertain the notion that choice is a panacea...It has the capacity all by itself to bring about the kind of transformation that, for years, reformers have been seeking to engineer in myriad other ways." Chubb and Moe are gifted thinkers, and their book was a tour de force, but this may have been some of the worst advice that school reformers ever got. The search for that panacea, and the insistence that it must be just around the corner, have been destructive distractions. They have led champions of market-oriented reforms -- and so also allowed skeptics -- to adopt a ludicrous standard for judging whether school choice "works." Since reformers have suggested that the mere presence of choice will bring about dramatic improvement in schools, the expectation has been that the simple fact of having an alternative -- even inadequately funded vouchers, or charter schools hog-tied by regulation -- should yield demonstrable gains in academic achievement. And so, for the past 20 years, the question of whether school choice "works" has been understood to mean simply whether a school-choice program boosted reading and math test scores in a given year. The need to answer this question with an unequivocal "yes" has forced choice advocates into bizarre contortions and short-sighted thinking. The same can be said of opponents, whose insistence, in the face of all evidence, that school choice is harmful has led them to ignore its real achievements. Particularly problematic is how this way of thinking has caused school-choice proponents to ignore crucial questions of market design and implementation -- especially the extent to which reforms have, or have not, created a real market dynamic in education. The chief promise of choice, after all, was that it would displace ossified, monopolistic school bureaucracies or at least inject into them a degree of flexibility, competition, and quality control. The question education reformers should be asking, then, is not simply whether choice "works" -- because choice is neither the sole end of nor a sufficient means for bringing about successful market-based reform. The questions to focus on are when, how, and why deregulation and monopoly-busting improve the quality and cost effectiveness of goods and services -- and whether they can do the same for K-12 schooling. What would a vibrant market in K-12 education look like? To what degree has it really been tried? What needs to change in order to bring about such a market, and how would we assess whether it is in fact improving the education received by children in America's schools?"