American merchants and reformers Arthur (1786-1865) and Lewis (1788-1873) Tappan were religious moralists and abolitionists who helped create important new institutions.

Born in Northampton, Mass., Arthur and Lewis Tappan were among the 11 children of a goldsmith and merchant. Their mother kept a strict Calvinistic household. Both Arthur and Lewis early showed aptitude for business and rose rapidly as wholesale and retail merchants in Boston and Canada. Arthur, a stern man, moved to New York, where he attained wealth in selling silks and a reputation for social and religious concerns. His most notable innovation was the one-price system on sales. Lewis, a warmer and more expressive personality, was won over by the Reverend William Ellery Channing and troubled his family by becoming a Unitarian. His return to Calvinism in 1828 created a sensation in Boston and beyond.

In 1827 Lewis joined Arthur in New York. They became influential in numerous fields...