Of all of America's religious communities, few seem less likely to thrive in the 21st century than the Old Order Amish. They are forbidden not only to drive tractors and automobiles but also to install electrical wiring in their homes and businesses. Yet their numbers are doubling every 20 years, and there are 1,600 Amish-owned businesses in Lancaster County, PA, alone, according to Donald Kraybill, author of The Riddle of Amish Culture and coauthor of Amish Enterprise. He notes that more than 90 percent of Amish youth accept baptism and its obligations.

As Kraybill and others have shown, the Amish are so resilient in part because their society tempers discipline with flexibility. Within the decentralized leadership, each bishop allows experimentation before deciding whether an innovation will be sanctioned by the community's Ordnung -- its oral body of customs and rules. For example, the bishops have generally permitted the use of electrical inverters in Amish shops so they can operate standard 110-volt AC machines like cash registers and typewriters with 12-volt batteries. The Amish receive modern medical care and encourage scientific study of their genetic diseases. Many of their famous black buggies are made of fiberglass. And some unbaptized youths experiment with automobiles and computers for a few years of rumspringa (running around) before they decide whether to join the church.