TOPEKA, Ind. -- Dan Bontrager is a 54-year-old Amish man with flecks of gray in his long beard. He's also treasurer of the Tri-County Land Trust, an Amish lending cooperative created to support the Amish maxim that community enhances faith in God.

This past spring, Mr. Bontrager was startled when a number of men he has known most of his life tied their horses to the hitching post outside his office and came inside to withdraw their money from the Land Trust.

"We...