The idea that one of the Catholic Church's most respected religious orders might run a public school sounded odd, maybe even, as Francis Cardinal George, head of the Archdiocese of Chicago, conjectured, illegal. But a decade ago several trends in American education, and in the Catholic Church, made a Catholic-operated public school seem increasingly possible: (1) the traditional, parish-based Catholic school system, especially in the inner cities, was crumbling; (2) equally troubled urban public-school systems were failing to educate most of their students; and (3) a burgeoning charter school movement, born in the early 1990s, was beginning to turn heads among educators in both the private and public sectors. The various currents merged in the Windy City in 2006 and 2007 when the Christian Brothers helped open two charter schools in impoverished neighborhoods on Chicago's west side, embarking on a unique experiment in public education. The Christian Brothers--known in France, where the Catholic order was founded in 1680, as "Freres des ecoles chretiennes" or Brothers of the Christian Schools--have had some experience in education. The author discusses how the Christian Brothers came to start two charter schools in Chicago, and the lessons they have learned along the way.