Nearly two decades have passed since the Wisconsin legislature enacted the landmark Milwaukee Parental Choice Program. Advocates had hoped and promised that this experiment in school choice would lead the way in transforming American schools. But it is clear by now that voucher programs and charter school laws have failed to live up to their billing. Frederick M. Hess, editor of the recent volume "The Future of Educational Entrepreneurship," argues that market-based reforms have not delivered because they were never designed to succeed. The challenge for champions of choice is to understand what happened and what comes next. (Contains 18 endnotes.)