Home schooling, not a present threat to public education, is nonetheless one of the forces that will change it. If the high estimates of the number of children in home schools—1.2 million or higher—is correct, then the home schooling universe is larger than the New York City public school system and roughly the size of the Los Angeles and Chicago public school systems combined. Even if the real number of home schoolers is more like 500,000, fewer than the lowest current estimate, there are more children home schooling than in charter schools and public voucher programs combined. 1 Home schooling is not a new phenomenon, but a very old one. In Colo-nial days, families, including wealthy ones, educated their children at home, combining the efforts of parents, tutors, and older children. The ru-ral one-room schoolhouse was created by families that banded together to hire a teacher who could substitute for parents but would still use the same mixture of direct instruction, tutoring, and mentoring by older students. 1 The best estimates of the numbers of home schools are provided by Lines (1998) and Bruno and Curry (1997). There is nothing un-American about home schooling. Home schooling families, however, are breaking a pattern established since Colonial times of education's becoming more and more institutionalized, formal, and re-moved from the family. How important is the contemporary home school-ing movement, and what does it portend for American public education? No one can say for sure. It is difficult even to estimate the numbers of chil-dren being schooled at home, and evidence about student learning and other outcomes is incomplete. It is possible, however, to draw three conclusions about where home schooling is likely to go and how it will affect the broad public education enterprise—which, for the purpose of this article, includes charter schools and publicly funded voucher programs as well as conventional dis-trict-run public schools. 2 • First, home schooling is part of a broad movement in which private groups and individuals are learning how to provide services that once were left to public bureaucracies. • Second, as home schooling families learn to rely on one another, many are likely to create new institutions that look something like schools. • Third, although many home schooling families are willing to accept help from public school systems, the families and the schools they create are far more likely to join the charter and voucher movements than to as-similate back into the conventional public school system.