issue that most people feel strongly about in one direction or another. True believers of school choice argue that their tax dollars buy them the right to send their children to the best school possible. Critics worry that school choice will leave behind the worst students in the worst schools. Still, just about every parent seems to believe that her child will thrive if only he can attend the right school, the one with an appropriate blend of aca- demics, extracurriculars, friendliness, and safety. School choice came early to the Chicago Public School system. Thats because the CPS, like most urban school districts, had a dis- proportionate number of minority students. Despite the U.S. Su- preme Courts 1954 ruling in Brown v. Board of Education of Topeka, which dictated that schools be desegregated, many black CPS stu- dents continued to attend schools that were nearly all-black. So in 1980 the U.S. Department of Justice and the Chicago Board of Edu- cation teamed up to try to better integrate the citys schools. It was de- creed that incoming freshmen could apply to virtually any high school in the district. Aside from its longevity, there are several reasons the CPS school- choice program is a good one to study. It offers a huge data set- Chicago has the third-largest school system in the country, after New York and Los Angeles-as well as an enormous amount of choice (more than sixty high schools) and flexibility. Its take-up rates are ac-   cordingly very high, with roughly half of the CPS students opting out of their neighborhood school. But the most serendipitous aspect of the CPS program-for the sake of a study, at least-is how the school-choice game was played. As might be expected, throwing open the doors of any school to every freshman in Chicago threatened to create bedlam. The schools with good test scores and high graduation rates would be rabidly over- subscribed, making it impossible to satisfy every students request.