Sharon and David Williams once viewed their children as Christian missionaries to their public-school system.

Yet in 1982, Sharon, herself a former public-school teacher, re-evaluated that stance in light of her children's three hours daily on a school bus, inadequate instruction, harmful peer influences, and, in one case, a sexually explicit film in French class.

After considering a private Christian school, the Williamses deemed the $500 per month for four children as unaffordable. Sharon Williams, looking at the alternatives, eventually determined to educate her children herself. Today, 13 years later, those children have completed high school and are in college, trade school, or the work force. Another seven Williams children are learning in their Lombard, Illinois, home.

Initially, David Williams says he struggled with whether his wife could handle teaching and whether the children would still adapt to society. "It's an incredible stress on the mother," he says. "But we wanted to move in the direction of our convictions."

MOVEMENT GOES MAINSTREAM: While an estimated 80 percent of the one million home-educated students in the United States are Christian, reasons for opting out of public education now extend beyond religion.

As doubts about the effectiveness of public education have grown, home schoolers have, by default, found themselves at the forefront of educational innovation. They have been busy in the home classroom experimenting with fresh teaching methods, integrating computer technology, partnering with colleges, and, in some cases, imparting religious instruction.

Home schooling has become a far more manageable exercise with new curriculums on the market, greater access to public-school programs, and a boom in affordable ...