Christian religious organization established to provide spiritual, physical, and social assistance to the poor and needy. It originated in the city mission movement among evangelical laymen and ministers early in the 19th century. The work of city missions resembles that of settlement houses, institutional churches, and charitable societies, but city missions usually also emphasize religious conversion through evangelistic preaching services.

In Great Britain (United Kingdom) the Glasgow City Mission (1826) and the London City Mission (1835) both sought to evangelize and rehabilitate the urban poor. Beginning with home visitation and tract distribution by volunteer lay missionaries, the city mission movement expanded into Sunday school, day school, and temperance activities with paid missionaries; and eventually it provided food, lodging, employment, and medical care for the destitute and sick. After 1865 the work of William Booth (Booth, William) and the Salvation Army brought a new impetus to city mission work in both Great Britain and the United States.

In Germany, Johann Hinrich Wichern, a Lutheran pastor and teacher, founded a rescue village near Hamburg for delinquent boys in 1833. At a Kirchentag (church rally) of the German Evangelical Church in Wittenberg in 1848, Wichern urged that the church minister to the physical and social needs as well as the spiritual needs of people. As a result the Central Committee for the Inner Mission was formed in 1849, and Inner Mission societies were formed in Germany's large cities and in the territorial churches.

In the United States the New York City Mission and Tract Society began home visitations in the 1830s and founded its first mission station in 1852. The movement flourished in the late 19th century and was established in other countries in Europe, including France, The Netherlands, the Scandinavian countries, and Poland. Most city missions have been founded and supported denominationally or interdenominationally, but some of the most successful have been nondenominational.