Christian Endeavor, association in evangelical Protestant Churches for strengthening spiritual life and promoting Christian activities among its members. The first Young People's Society of Christian Endeavor was started in 1881 by Dr. Francis E. Clark in Portland, Maine. Within a few years the organization had become not only interdenominational but international, and a world union was formed in 1895, with Clark as president. Started primarily as a youth movement, the association now includes all age groups and numbers in the millions. Many denominations are represented in the association's membership.